Republican, 1864-75
Republican 1887-1893
Silver, 1893-1901
Republican, 1901-1905

The issue of remonetization of silver brought about party changes for several senators, including William Stewart of Nevada. As a delegate to the Republican party's national convention in 1888, Stewart drafted the currency plank for the party's platform, which was later abandoned. Predicting the Republicans would adopt a gold standard plank in its 1892 platform, Stewart refused to be a delegate to the Republican national convention that year. As he noted in his memoirs:

After my experience with Harrison's Administration I found it would be impossible for me to further indorse the Republican party without indorsing the crime of John Sherman in demonetizing silver. When it became evident that Benjamin Harrison would be nominated his own successor in 1892, I severed my connection with the Republican party and joined my fellow-citizens of Nevada in the organization of a silver party....

The two major parties avoided close association with the silver issue at their 1892 conventions, and the Democrats nominated the pro-gold standard Grover Cleveland. In response, various pro-silver factions met in Reno in June of 1892, resulting in the Silver League -- not an official political party, but an entity often referred to as the Silver party. (The pro-silver "People's Party" was being formed simultaneously in Omaha, and Nevada established a Silver party in September 1892.) Stewart was re-elected to the Senate on a Silver party ticket for the term beginning in 1893. Evidently, although this has been difficult to document, Stewart left the Republican caucus at that time. According to Elmer Ellis (Henry Moore Teller: Defender of the West), after the 1896 election, "the Silver Republican senators were invited to join the caucus of the Republicans, but refused," implying that they had all left the caucus when they switched parties.

Stewart's return to the Republican party was gradual. Bryan's defeat in 1896, and then the discovery of large reserves of gold depoliticized the silver issue. Stewart drifted back to his old political base within the Republican party. He rejoined the Republican caucus on December 4, 1899, at the beginning of the session. In 1900 he supported William McKinley for the presidency, and backed a Republican candidate for the House, further distancing himself from the Nevada Silver party. No specific date has been found to mark his return to the party, but clearly the transfer was complete by the election of 1900.

Stewart's switch to the Silver party certainly caused tension within the Republican party, and there is evidence to suggest that it had some impact on his committee status. As Stewart commented in his memoirs:

After the silver question was eliminated from politics, having been a Republican from the organization of that party I returned to my natural allegiance, and entered upon the campaign with the Republican Party in 1900.... They restored to me positions on committees which were reserved for the dominant party. Among other things, they made me chairman of the Committee on Indian Affairs, one of the leading committees of the Senate.

His use of the word "restore" suggests he had been demoted although he maintained membership on committees. After returning to the party, Stewart was rewarded in 1901 with the chairmanship of the Indian Affairs Committee, a position of importance to him. (At the same time, he relinquished his chairmanship of the Mines and Mining Committee.) Although he was welcomed back into the party fold, Stewart was widely criticized in his home state for abandoning the young Silver party.

Republican, 1873-1895
Silver, 1895-1901
Republican, 1901-1903

Like Stewart, fellow Nevadan John P. Jones became closely associated with the silver issue in the late 1880s. At the 1892 Republican party convention in Minneapolis, Jones told delegates that the silver issue had reached "the proportions of a third party" in Nevada and could result in a "clean bolt on election day." (This predicted "bolt" would come with the 1896 convention instead.)

The move to repeal the Sherman Silver Purchase Act in 1893 prompted a Senate filibuster that thrust Jones into the political limelight. In October of that year, he delivered a speech that continued, with interruptions, over an eight-day period, taking up over 100 pages in the Congressional Record. The speech became the pre-eminent statement of the Silverites. Despite Jones' efforts, however, both houses of Congress supported President Grover Cleveland and voted to repeal the Sherman Act.

It was the repeal of the Sherman Act that prompted Jones to make a decisive break with the Republican party. At first, he considered the new Populist party, which had backed the silver issue and had made a good initial showing in the 1892 election. By 1894, however, he clearly leaned towards a Silver party. In August of that year, he appeared along side William Jennings Bryan at the conference of the American Bimetallic League. On September 4, 1894, Jones officially announced his decision to leave the Republican party, and authorized the publication of his letter to the chairman of the Republican State Central Committee in Nevada, in which he stated:

Having become fully convinced that the republican party organization is unalterably opposed to the free coinage of silver at the American ratio of 16 to 1 ... I have to announce that I can no longer act with that party. ...A change of party affiliations is not to be either advised or commended except in obedience to the imperative demands of principle. But I submit to my friends and all who believe with me that in this great emergency the monetary issue is ... the supreme, if not the sole issue, which should now be deemed to be before the country. That being so, I ask whether, with the principles which they really entertain, they are not doing more violence to their consciences by remaining in the old party organizations than they would do by joining a party which, though new, has the courage of its convictions. In a subsequent interview, Jones explained, "I can no longer as an honest man, true to my convictions, remain with a party whose principles on the main issue are so repugnant to my own views."

The 1896 Republican convention in St. Louis left little doubt that silver was not on the Republican agenda. The party nominated Wiliam McKinley and adopted a pro-gold standard platform that so angered the Silver Republicans that they bolted from the convention (see below). McKinley's defeat of pro-silver William Jennings Bryan, coinciding with new discoveries of gold, effectively buried the silver issue by the turn of the century. The Republican party won a clear majority in the Senate, further diminishing the importance of the Silver Republicans as a political force. With the power safely on their side, Republicans reached out to the dissident group. As noted above, Ellis reported that after the 1896 election "the Silver Republican senators were invited to join the caucus of the Republicans, but refused." It is probable that Jones opted not to rejoin the caucus in 1897.

With the silver issue all but dead after the 1900 election, Jones -- like Stewart -- returned to the fold of the Republican Party. At the time Jones left the party, he was chair of the Committee on Epidemic Diseases. With the 54th Congress (1895-1897) he became chair of the Committee to Audit and Control the Contingent Expenses of the Senate, a position he maintained throughout the period of his party change and for the remainder of his Senate career (ending in 1903), indicating no adverse affects of his party change on committee assignments. Although we do not have documentation for this, it is probable that Jones returned to the Republican caucus after his return to the party.

Republican, 1876-1881
Republican, 1885-1897
Silver Republican, 1897-1901
Democrat, 1901-1909

Teller bolted from the Republican Convention on June 17, 1896, over the issue of remonetizing silver, to join the insurgent party of the Silver Republicans. There were indications at the time that he was considering a run for the presidency on the Democratic ticket, but when Bryan emerged as the frontrunner he joined the Republicans instead. Teller reluctantly endorsed the Democratic nominee (pro-silver William Jennings Bryan) in 1896 and 1900. After bolting the party in 1896, Teller left the Republican caucus. He was invited to rejoin the caucus several times between 1896 and 1900, but refused. As silver diminished as a political issue, the Republican party hoped to bring the silver dissidents back to the party. While some returned to the fold, Teller gradually distanced himself from the Republican party, having, as Elmer Ellis noted, burned his bridges with the party (Henry Moore Teller: Defender of the West). At the end of the 55th Congress in March 1901, Teller announced that he would begin the next Congress as a Democrat.

Teller's party changes seem to have had little impact on committee assignment or seniority status. Ellis wrote that "Neither inwardly nor outwardly was there any marked change in Teller's life after transferring his party membership." The main difference, of course, was that he was in the minority party for the rest of his career. Teller maintained his chairmanship of the Committee on Claims through the transition from Republican to Silver, and maintained his chairmanship of the Committee on Private Land Claims throughout the transition from Silver to Democrat, despite the fact the Republican party retained the majority during each of these times. These were considered minor committees, however, and not often sought by majority members.

Republican, 1895-96
Silver Republican, 1896-1899

Mantle bolted from the Republican party convention on June 17, 1896, along with Teller, Pettigrew, and Cannon, to join the Silver Republicans. Like the others, he left the Republican caucus with his switch to the Silver party, and refused to rejoin after the 1896 election. Mantle, perhaps more than the others, seemed to favor a return to the Republican party by 1900, but he lost his bid for reelection that year. There is no evidence to suggest an impact on committee assignments, but he was a junior senator without important assignments at the time of his defection.

Republican, 1889-1896
Silver Republican 1896-1901

Pettigrew left the Republican party on June 17, 1896, to join the Silver Republican party with Teller, Mantle, and Cannon. Claiming the Republican party was "in the hands of trusts and corporations," with a platform authored by "gamblers and Shylocks," Pettigrew turned to the newly organized Silver Republicans.

Pettigrew failed to gain re-election in 1900. He left the Senate to return to private business, giving his subsequent political allegiance to the Populists until that party's demise, then he became a Democrat. (He made an unsuccessful bid for a Senate seat as a Democrat.) Eventually, he joined the Socialist Party.

Like his fellow Silver Republicans, Pettigrew left the Republican caucus and did not rejoin. Since he retained his committee chairmanship after his party change, no impact on committee assignment is noted.

Republican, 1896-1896
Silver Republican, 1896-1901

Frank J. Cannon grew up in a political household in Salt Lake City, Utah. His father, George Q. Cannon, was a territorial delegate to Congress, and served the Mormon Church as its first councillor from 1880-1901. The younger Cannon became involved in politics in 1888 when he worked to modify federal polygamy laws aimed at the Mormon population. Three years later, Cannon helped organize the Republican party in Utah, and was one of Utah's first delegates to a National Republican Convention. Following an earlier unsuccessful campaign, Cannon won the territorial delegate's seat in 1894. When Utah entered the Union in 1896, he became the state's first U.S. senator.

Cannon joined other western senators in bolting the Republican party convention in 1896, and joined the Silver Republican movement. Cannon further alienated himself from regular Republicans by opposing the high protectionist Dingley Tariff.

Despite his party change, he retained all committee assignments and was not disciplined in the Senate. In 1899, Cannon's short term expired. Despite being backed by a combination of Silver Republicans, Populists, and Democrats, he was not reelected to the Senate.

Republican, 1891-1897
Silver Republican, 1897-1901
Democrat, 1901-1907

Fred T. Dubois switched parties twice during his Senate career. As a Republican, he assisted Idaho's transition into statehood in 1890. Later that year, the new state legislature elected him to be one of Idaho's first senators. He served in the Senate as a Republican between 1891 and 1897, and headed his state's delegation to the Republican National Convention in 1892 and 1896. At the second convention, Dubois and other pro-silver Republicans left in protest. He lost his 1896 bid for reelection.

At the turn of the century, Dubois led Idaho's Silver Republicans into an alliance with the Democrats, and soon became a rising figure in the Democratic party, although choosing to remain a Silver Republican candidate in the 1900 Senate race. Dubois was reelected in 1900 as a Silver Republican, but officially became a Democrat shortly afterwards. He served one term, from 1901 to 1907, and did not seek reelection.

By the end of his first term, Dubois chaired the Public Lands committee as a member of the Republican majority party. It is possible that he would have won reelection, had he not bolted the party convention. During his second term as a Democrat, he was a member of the minority party. Consequently, he did not chair any committees during his second term.

Dubois' party change took place while he was out of office. He was elected to the Senate as a Silver Republican, then changed to a Democrat before taking his seat. Democratic Minutes show him attending the Conference in December of 1903. He was on the Democratic Steering Committee in June of 1906. He probably suffered no negative effects of the change since it came at beginning of his second service in Senate.

Republican, 1911-1913
Progressive, 1913-1915
Republican, 1915-1923

Miles Poindexter began his career as a Democrat, serving as a prosecuting attorney in Walla Walla, Washington. When Democrats promoted Populist doctrines in the late 1890s, he switched his allegiance to the Republican party. In 1897, Poindexter moved to Spokane, where he became active in state and regional politics. A critic of the free silver movement, Poindexter lobbied for progressive measures, especially the regulation of northwest railroads. In 1910, he won the Republican Senate primary, despite his public opposition to President William Howard Taft and the Payne-Aldrich tariff. While Taft disparaged his campaign by commenting, "a more blatant demagogue and Democrat never existed," Poindexter received the endorsements of both business and labor leaders before the Washington state legislature voted him into office.

During the election of 1912, Poindexter supported Theodore Roosevelt's efforts to win the Republican presidential nomination. Although he wanted Roosevelt and other progressive candidates to remain Republican, Poindexter continued to campaign for Roosevelt on the Progressive party ticket. Poindexter officially joined the Progressive party when western Washington politicians organized a Progressive convention. While many of his colleagues shared his reform-minded views, he was the only sitting senator to register as a member of the Progressive party.

Poindexter's third-party membership proved to be short lived. In 1915, he returned to the Republican party, and was reelected to the Senate on a Republican ticket in 1916. As a "regular" Republican, he sided against workers in labor disputes, led the red scare in 1919 and 1920, and opposed America's entry into the League of Nations. In 1919, he ran for president, but his anti-socialism and anti-labor platform received little support. In fact, many of his later policies alienated him from the progressive agenda he once supported. Clarence C. Dill, a progressive Democrat, defeated Poindexter in 1922. Six years later, Poindexter ran again, but did not win the Senate primary election.

While Poindexter's change in viewpoint – from progressive to conservative – hurt him at the polls, party switching did not have an apparent affect on his committee chairmanships. As a Republican in the 62nd Congress (1911-1913), he chaired a different Senate committee each sessiono. The following Congress, he chaired the Committee on Expenditures in the War Department while listed as a member of the Progressive party. He rejoined the Republican party for the 64th Congress but did not chair a committee, because the Republicans were in the minority. The Republican party regained the majority in the 65th Congress, and Poindexter chaired the Committee on Indian Depredations before returning to the Committee on Mines and Mining for the 66th and 67th Congresses. The only visible impact of his party change seems to be that he stopped attending the Republican Conference meetings during that time.

Republican, 1906-1925
Ran as Progressive in 1924 presidential election

In 1924, Robert M. La Follette, who served in the Senate as a Republican, ran for president on the Progressive party ticket. Early that year, La Follette was denied the chairmanship of the Interstate Commerce Committee by the Republican caucus. His role in the Progressive party was cited as the reason for the denial. After the election, in November 1924, the Senate Republican Conference demoted La Follette from the chairmanship of the Committee on Manufactures to the next to last place on that committee. Three other Republican senators who had also supported the Progressive ticket were no longer invited to meetings of the Republican Conference or named to fill Republican vacancies on Senate committees, although they did not change their party affiliation.

Republican, 1925-1935
Progressive, 1935-1947

In 1925, when Robert La Follettee, Sr., died in office, Robert La Follette, Jr. filled that vacancy. As a progressive Republican from Wisconsin, the younger La Follette soon distanced himself from the views of "regular" Republicans in Congress. During his successful reelection campaign in 1928, he publicly opposed Herbert Hoover's presidential candidacy, and later criticized the president's handling of the economy at the onset of the Depression. La Follette supported Franklin Roosevelt for president in 1932. In the early 1930s, Wisconsin's Republican party became more conservative, and progressive members left the GOP to form the Progressive party. La Follette and his younger brother, Philip, led the Progressives to election victories in 1934. Despite switching parties, La Follette was easily reelected to the Senate, and Philip, a former Republican governor, became the Progressive governor of Wisconsin. On January 2, 1935, the Republican Committee on Committees considered the changed political status of La Follette, deciding that his committee assignments would remain as they were before he switched parties. In other words, he would continue to receive his assignments through the Republicans, and accrue seniority in relation to Republican members.

From 1936 to 1940, La Follette chaired a special Senate investigating committee known as the La Follette Civil Liberties Committee. He gained national prominence as a senator sympathetic to labor when his committee exposed coercive techniques employers used to keep workers from organizing. His popularity within Wisconsin declined by the end of his chairmanship, however, and he managed to win reelection in 1940 by just a narrow margin. La Follette returned to the Republican party prior to his last Senate race in 1946. Rather than campaign in Wisconsin, however, he remained in Washington to complete work on the La Follette-Monroney Legislative Reorganization Act. This major legislation streamlined the committee system and provided greater staff assistance to House and Senate members. This work may have cost La Follette the election, however, since he had no time to reestablish ties with the Wisconsin Republican party. He lost the 1946 primary to Joseph McCarthy.

La Follette suffered little damage within the Senate for switching parties. During the 71st Congress (1929-1931) La Follette chaired the Committee on Manufactures. In the 73rd Congress (1933-1935), after the Democrats took over the Senate, conference minutes show that La Follette did not attend the Republican Conference, but he is listed with Republican committee assignments. In the 74th Congress (1935-1937) the Republican Conference invited him to attend. He was included on the Republican committee assignment lists. La Follette retained his seniority and is listed in the comparable position on each of his committees in this Congress as in the previous Congress. The minutes of the Republican Committee on Committees of Jan. 2, 1935 state:

The committee considered the situation arising from the changed political status of Senator La Follette, who held certain places of fixed priority as a Republican on the committees and had been reelected as a Progressive....

   It was moved by Mr. Couzens:

   That the location of Senator La Follette on his committee assignments remain as they are; and the question being put by the Chairman, it was unanimously carried.

Eventually, La Follette became the most senior Republican on Finance, Education and Labor, Indian Affairs, and Manufactures.

Republican, 1913-1937
Independent, 1937-1943

George Norris moved to Nebraska in 1883, where he served as a county prosecuting attorney, and later as a district judge. A Republican in a Populist stronghold, he won election to the House of Representatives in 1902. Although railroad officials helped his campaign, Norris eventually broke ties with this segment of the business community. He backed Theodore Roosevelt's domestic policy, including new regulations for railroads.

In 1908, Norris joined the House "insurgents," a group of Republican members critical of Speaker Joe Cannon's rule over the House. As a consequence of the Cannon revolt, Norris lost some desirable committee assignments and barely won his next reelection, having received little support from the Republican party. Norris further alienated himself from the party "regulars" in 1910 when he sponsored a resolution establishing an elected Rules Committee not controlled by the speaker.

The National Progressive Republican League was created in 1911 to encourage the nomination of a reform-minded candidate for the upcoming presidential election. Norris became the League's first vice president. At the start of the campaign, he supported Robert La Follette, Sr.'s Republican candidacy, then shifted his allegiance to Theodore Roosevelt and the Progressive party, even though Norris did not join Roosevelt's new party. Instead, he ran for the Senate as a Republican, and won the general election in 1912.

In the Senate, Norris backed some of Woodrow Wilson's domestic measures, but did not like the new president's foreign policy. He was one of six senators to vote against the American declaration of war. In 1917, Norris became known as a Senate "irreconcilable" for publicly opposing the Versailles Treaty. During the 1920s, he chaired the Agriculture and Forestry and the Judiciary committees, but his unorthodox views separated him from his Republican colleagues. Norris advocated farm relief, the rights of labor, the development of natural resources, and direct presidential elections, while he openly criticized the Republican administrations under Harding, Coolidge, and Hoover.

In 1928, Norris endorsed Hoover's Democratic rival, Alfred E. Smith, for the presidency, and campaigned for progressive senators from both major parties. Two years later, a number of Republicans tried to sabotage his reelection efforts, but they failed to unseat Norris in the primary. Norris supported all of Franklin Roosevelt's presidential campaigns, as well as most of the New Deal measures. As a nominal Republican, he drafted the Twentieth Amendment, created the Tennessee Valley Authority, and co-authored the Rural Electrification Act.

Norris left the Republican party in 1936, and successfully ran for the Senate as an independent, earning the endorsement of FDR and the Nebraska Democratic Party. Six years later, Roosevelt again supported Norris' independent bid, but this time Nebraska Democrats backed their own candidate for the Senate, splitting the vote, and Norris lost the election to a Republican. While Norris' independent status probably hurt him at the polls, it did not affect his committee assignments. During his last term in office, he remained the ranking member on Agriculture and Forestry and Patents, and the second ranking member of the Judiciary Committee.

Norris is not listed in the Republican Minutes as attending the Conference in the 75th Congress (1937-1939), after his party change. (In fact, he had not attended the conference since 1931.) He did continue to receive his committee assignments from the Republican party. Prior to his party change, Norris was ranked second in Republican seniority and was the ranking Republican on Agriculture and Forestry, and Patents, and second ranking on Judiciary. After his change, he retained those positions in the 75th Congress.

Farmer-Labor, 1923-1941
Republican, 1941-1947

Henrik Shipstead began his political career as the mayor of Glenwood, Minnesota, and later became active in regional, agrarian politics. In 1917, he served in his state's legislature, but lost subsequent elections for Congress and for governor. He remained involved in farmers' organizations, however, and joined the Farmer-Labor party after it split from the Non-Partisan League in 1920. Two years later, Minnesota voters elected him to the Senate.

In the Senate, Shipstead lobbied for Farmer-Labor domestic policies including government ownership of some industries, social security, and protection for farmers and union workers. When his own party dwindled in membership, he aligned with western and rural progressives against eastern financial interests. He especially opposed concentrated power in large companies, and criticized the Republican administrations for their pro-business policies.

Prior to his reelection in 1940, Shipstead switched to the Republican party, but maintained his reputation as an independent thinker. A strong isolationist, he was against U.S. membership in the World Court and the League of Nations, and would eventually be denounced as an "appeaser" for his attempts to keep America out of the European war. After the attack on Pearl Harbor in 1941, he publicly supported the war, but fought to minimize U.S. involvement in foreign affairs. In 1945, he was one of only two senators to vote against the United Nations charter. The following year, he did not win his reelection bid to the Senate.

Shipstead's switch to the Republican party had minimal effect on his position within the Senate. As a Farmer-Labor senator, he received his committee assignments from the Republican leadership. He raised his rank in several committees after he joined the Republican party. The elevated status probably came as a result of attrition, however, and not as a reward for switching parties. By that time, he had begun to lose the support of senators and constituents who found his isolationist views and rural values inappropriate for war-time America. Following the war, Shipstead's well-publicized vote against American membership in the United Nations sealed his Senate defeat in 1946.

Even while he belonged to the Farmer-Labor party, Shipstead had been invited to attend Republican Conferences since the 74th Congress, although he is not listed in the minutes as ever actually attending. He had received his committee assignments from the Republican party and his name was listed in the Congressional Directory in the Republican column (although in a different type face). In the 74th Congress the Conference Minutes list him as being 9th in seniority within the party. With his switch to the Republican party in 1941, he began attending Republican Conferences.

Republican, 1945-1953
Independent, 1953-1955
Democrat, 1955-1969

An expert on law and labor arbitration, Wayne Morse worked for the Attorney General and the Secretary of Labor before Franklin Roosevelt appointed him to the National Labor Board in 1942. Despite his close association with Roosevelt and the New Deal, Morse began his political career as an Oregon Republican. He beat the GOP incumbent in the Senate and won the general election. As a freshman senator, he was assigned to numerous committees, including Armed Services and the Labor and Public Welfare Committee, chaired by Robert Taft in the following Congress. In 1947, Morse surprised Republicans by challenging Taft on the Taft-Hartley bill, which placed restrictions on labor unions' right to strike and organize. Shortly after his reelection in 1950, Morse criticized economic measures favored by most Republican members. Rebuffed by his colleagues at the Republican National Convention, he cast an absentee ballot for Adlai Stevenson, the 1952 Democratic presidential candidate. At that time, Morse resigned from the Republican party and started campaigning for Stevenson.

When the 83rd Congress commenced in 1953, Morse listed himself as an independent. As the only third-party member on the Senate floor, he did not know where to sit, and set up a folding chair in the aisle between the Republican and Democratic sections. Eventually, he settled on the Republican side of the aisle.

More damaging to his career was his loss of committee assignments. Had he accepted committee assignments from either of the parties, he may have retained his positions on Labor and Armed Services -– both desirable committees and suited to his abilities. Instead, Morse asked that the Senate at large vote for or against his placement on the committees of his choice. Following three ballots on Morse's proposals, the Senate assigned him to the "leftover" committees, District of Columbia and Public Works.

Though last in seniority on both his committees, Morse asserted his influence in the committee rooms and on the Senate floor. He became a strong advocate of "home rule" in Washington, and gained prominence as an orator. In April 1953, he delivered a twenty-two hour, twenty-six minute speech against a tidelands oil bill, marking the longest recorded filibuster prior to Strom Thurmond's opposition to the Civil Rights Act of 1957.

On February 17, 1955, Morse joined the Democratic party, and helped the Democrats take control of the Senate. The new majority leader, Lyndon Johnson, assigned Morse to a coveted spot on the Foreign Relations Committee. As a Democrat, he received retroactive seniority dating to November 8, 1954, and was reelected to the Senate in 1956 and in 1962. In 1964, Morse and Ernest Gruening were the only two senators to vote against the Gulf of Tonkin Resolution, intensifying U.S. involvement in Vietnam. That vote, coupled with Morse's decision to back Eugene McCarthy's unpopular anti-war campaign, hurt Morse's reelection efforts in 1968. He narrowly won the Democratic Senate primary, and lost the general election to Republican state representative, Bob Packwood. In 1972, he won the Democratic nomination once again, but was defeated in the general election by Mark Hatfield. Morse tried one more time to win the general election in 1974, but died of kidney failure before he could run against Packwood as the Democratic nominee.

For Morse, party switching resulted in significant consequences, both negative and positive. After he bolted from the Republican party, Morse lost his seniority and his positions on two prestigious committees. He compounded his difficulties by being the lone independent senator in a two-party system. Later, Morse was rewarded for joining the Democratic party. He received a coveted position on the Foreign Relations Committee, and later became chair of the Labor and Public Welfare Committee's Subcommittee on Education. Morse's Senate defeats in 1968 and 1972 were due largely to his stance on foreign policy issues and his advancing age, not his history of switching parties.

Before his first party change, in the 82nd Congress (1951-1953), Morse attended Republican Conferences. On committees, he was third ranking Republican on Armed Services and fourth ranking on Labor and Public Welfare. In the 83rd Congress, after his switch to Independent, Morse did not attend Republican Conferences and was not included on the party's list of committee assignments. In the Congressional Directory for the first session of the 83rd Congress, he is listed as having no committee assignments. By the second session he is listed as serving on District of Columbia and Public Works, in each case being placed last in seniority on the Republican side (Republicans were in the majority in that Congress.) In the 84th Congress (1955-1957) he became a member of the Democratic Conference. According to the minutes, on January 4, 1955,

Chairman [Lyndon] Johnson, of Texas, then raised the problem of floor seating arrangements for Senator Wayne Morse, of Oregon, of the Independent Party, who asked that his seat be moved from the Republican to the Democratic side of the aisle.

Chairman Johnson said that Wayne Morse had actually been granted a seat on the Democratic side of the aisle on November 8, 1954, but that the question of seniority for permanent seating arrangements still remained to be resolved. Senator Carl Hayden, of Arizona, moved that Senator Morse's seniority date from November 8, a move which was adopted unanimously by the Conference.

With Morse's help, the Democrats regained the majority in the 84th Congress. (His formal registration as a Democrat took place on February 17, 1955.) On each of his three committees, he was listed in the Congressional Directory as last in seniority on the Democratic side.

Independent Democrat, 1954-1956
Democrat, 1956-1964
Republican, 1964-2003

Thurmond met with the Democratic Conference from his arrival in the Senate, although he made clear that his election in 1954 had not been aided by the Democratic Senatorial Campaign Committee. (In April 1956 he resigned and ran again for his seat that November as a Democrat.) He was still attending Democratic Conferences as late as August 1964, but changed to the Republican party on September 16, 1964.

In the 88th Congress (1963-1965), Thurmond was the seventh ranked Democrat on the Armed Services Committee and the fourth on Commerce. In the 89th Congress (1965-1967), after his switch, he was the third ranking Republican on both Armed Services and Banking and Currency, indicating that his seniority status was maintained.

Democrat, 1965-1971
Independent, 1971-1983

Harry F. Byrd, Jr. followed his father into successful careers in apple farming, newspaper publishing, and Virginia politics. A former state senator, he was appointed to Harry F. Byrd, Sr.'s Senate seat when the elder Byrd retired in poor health in 1965. Campaigning as a Democrat one year later, he won the election for the four years remaining on his father's term.

In 1970, Byrd announced that he was leaving the Democratic party to become an Independent member of the Senate. Earlier, he had objected to a loyalty oath administered by Virginia's Democratic Central Committee. While the oath only applied to that year's general election, it may have restricted Byrd's choice for the president in 1972. Not wanting to be a "captive senator," he considered himself forced out of the Democratic party. Political commentators suggested, however, that Byrd left the party because he no longer commanded Virginia's Democratic base. As an Independent, they argued, Byrd could attract a wider electorate without having to face a challenger in the upcoming primary election.

Calling himself both an Independent and an Independent Democrat, Byrd won the six-year Senate term in the fall of 1970. In 1976, Virginia voters elected him to a third term by a large margin. Byrd decided not to seek a fourth term, and retired from the Senate on January 3, 1983.

After leaving his party, Byrd played no role in the Senate's Democratic leadership, but generally voted with the Democrats on procedural and party matters. He remained a member of the Democratic Caucus, and received his committee assignments from the Democrats. Although at least one Democratic senator objected to his status, Byrd's party switching had no impact on his seniority. He continued to move up in rank on the Armed Services and Finance Committees without reaching the position of chair or ranking member during his career in the Senate.

Democrat, 1987-1994
Republican, 1994-present

Richard Shelby left the Democratic party on November 9, 1994 to join the Republican party. He maintained his 8-year seniority status when he switched parties. Prior to his party switch he served on four committees (ranking number in parentheses):

Armed Services (7)
Banking (5)
Energy (7)
Special Committee on Aging (6)

After his party switch, his committee assignments changed to:

Appropriations (12)
Banking (3)
Special Committee on Aging (8)
Select Committee on Intelligence (2)

Democrat, 1993-1995
Republican, 1995-2005

Ben Nighthorse Campbell left the Democratic party on March 3, 1995, and joined the majority Republican party. His seniority was maintained. Prior to his party change his committee assignments included (ranking in parentheses):

Banking (9)
Energy (9)
Indian Affairs (10)
Veterans (7)

After his party change, his committee assignments were:

Agriculture (10)
Energy (6)
Veterans (6)
Indian Affairs (7)

Republican1990-July 13, 1999
Independent, July 13, 1999 to November 1, 1999
Republican, November 1999 - 2003

Smith left the Republican party on July 13, 1999, becoming an independent. Just a few months later, on November 1, 1999, he announced his return to the Republican party, noting that, since his home town in New Hampshire had not yet changed his voter registration, he had technically never left the Republican party.

Smith's return to the Republican party coincided with the death of Rhode Island Republican senator John Chafee, whose chairmanship of the Environment committee was then given to Smith.

Republican, 1989-2001
Independent, 2001-2007

Jeffords announced his change on May 24, 2001, effective June 6, 2001. He indicated that he would caucus with the Democratic party, thus changing control of the evenly divided Senate from the Republicans to the Democrats.

Democrat, 1989-2006
Independent Democrat, 2006-present

Lieberman was elected as a Democrat to the U.S. Senate in 1988, and reelected in 1994 and 2000. In 2006, he lost the Democratic primary and chose to run as an independent candidate, winning the election. He currently serves as an Independent Democrat.

Republican, 1981-April 29, 2009
Democrat, April 30, 2009-present

Specter was elected as a Republican to the U.S. Senate in 1980, and reelected in 1986, 1992, 1998, and 2004. In April of 2009, he decided to change party affiliation, and became a Democrat on April 30, 2009.