On March 6, 1903, the faction-ridden Senate Democratic caucus decided it was time to get organized. On that day, for the first time in the Senate's history, the caucus formally elected a chairman and a secretary, agreed to keep regular minutes of its proceedings, and took steps toward the adoption of a "binding rule."

When Republican President Theodore Roosevelt called the Senate into special session on March 5, 1903, to consider ratification of a Panama Canal treaty, the Democratic caucus unanimously selected Maryland's Arthur Gorman as chairman. The dominant figure in late nineteenth-century Maryland political life, Gorman was a masterful legislative strategist and party loyalist. Based on his informal service as Democratic leader in the 1890s, his Senate colleagues believed he was just the man to revitalize their heavily out-numbered party in the early 1900s.

Gorman convened the caucus on March 6, 1903, in the third-floor Capitol room now designated the "Senate Wives' Lounge." The newly elected secretary, Tennessee Senator Edward Carmack, presumably began to keep regular minutes. Although the formal record of that session has not survived, the following day's Washington Post provided a richly detailed account. The existing minutes begin with the meeting of March 16, 1903. Democratic senators who opposed the pending Panama Canal treaty sought to unite their party by proposing a rule that would bind all 33 members to any decision approved by two-thirds of the caucus. The action, agreed to later that year, marked the first time a party caucus sought to exercise such a binding rule.

Adoption of the binding rule promoted a distinction between the terms "caucus" and "conference." As these words came to be used, senators were in "caucus" when they discussed whether or not to bind the party's vote on a given issue; they were in "conference" when considering election of officers or general legislative business.