Missouri Republican Sen. Roy Blunt launched a new push Tuesday against changing the Senate rules with a simple majority, as advocates sought to explain the constitutional justification for the maneuver.

Blunt, the Republican Conference vice chairman, launched a website featuring statements from Democrats criticizing simple majority rules changes when proposed by Republicans in the past. Blunt and other Republicans argue that further changes would be inevitable beyond what Democrats currently propose, if the rules are changed without support of two-thirds of the chamber in January.

While only a simple majority would be needed to adopt new rules, the current rules allow such a proposal to be filibustered, with two-thirds required to invoke cloture and limit debate.

Blunt spoke at The Heritage Foundation Tuesday to build interest in his effort among conservatives. He expressed the view that a simple majority rules change would poison the well for future cooperation on routine chamber business that requires unanimous consent.

Even if Senate Democrats move forward with a package of changes using the simple majority procedure, the alterations currently under discussion would still have the Senate dependent on unanimous consent agreements.

Blunt said that he had heard discussion on the GOP side that “if our minority rights are taken away, we’re not going to go along with unanimous consent” that is required to get most routine business done. While he did not get into details, Sen. Mike Lee, R-Utah, expressed a similar sentiment last week. Blunt said that would lead Majority Leader Harry Reid, D-Nev., to make further changes in a future Congress, eventually leading to a majoritarian Senate.

Other senators renewed the battle over the “nuclear option” on the Senate floor Tuesday. Sen. Tom Udall of New Mexico, one of the leaders of the overhaul efforts on the Democratic side, sought to respond to a common GOP claim that he and other Democrats want to “break” the existing Senate rules.

“They say that any attempt to amend the rules by a simple majority is breaking the rules to change the rules. This simply is not true and repeating it every day on the Senate floor doesn’t make it true. The supermajority requirement to change Senate rules is in direct conflict with the U.S. Constitution,” he said. “The Constitution is very specific about when a supermajority is required, and just as clearly, when it isn’t required.”

Udall came to the Senate floor in response to a speech by Sen. Mike Johanns, a Nebraska Republican. Johanns made many of the same arguments as other GOP senators, but closed his formal remarks on an optimistic note.

“I hope between now and January cooler heads ... will prevail, and we will put ourselves back on a path to finding bipartisan solutions to our nation’s most pressing problems,” Johanns said.

Blunt said his goal is to find enough Democratic skeptics of the process that supporters call the “constitutional” option to cause both sides to step back and engage in negotiations.

“That’s why we elect a leader and they elect a leader,” he said, signaling that he would like to see Reid work out a deal with Minority Leader Mitch McConnell, R-Ky.

“There is growing concern on their part,” Blunt said of Democrats, adding that some up for re-election may not want to defend the “nuclear option.” Several Democrats have already expressed reservations about a simple majority plan, including Armed Services Chairman Carl Levin of Michigan.