WASHINGTON — Senator Mitch McConnell on Monday dropped his demand that the new Democratic Senate majority promise to preserve the filibuster — which Republicans could use to obstruct President Biden’s agenda — ending an impasse that had prevented Democrats from assuming full power even after their election wins.
In his negotiations with Senator Chuck Schumer of New York, the new majority leader, Mr. McConnell, Republican of Kentucky, had refused to agree to a plan for organizing the chamber without a pledge from Democrats to protect the filibuster, a condition that Mr. Schumer had rejected.
But late Monday, as the stalemate persisted, Mr. McConnell found a way out by pointing to statements by two centrist Democrats, Senators Joe Manchin III of West Virginia and Kyrsten Sinema of Arizona, that said they opposed getting rid of the procedural tool — a position they had held for months — as enough of a guarantee to move forward without a formal promise from Mr. Schumer.
“With these assurances, I look forward to moving ahead with a power-sharing agreement modeled on that precedent,” Mr. McConnell said in a statement.
Democrats had been anticipating a capitulation by Mr. McConnell and said they believed he had overreached in the negotiation.
“We’re glad Senator McConnell threw in the towel and gave up on his ridiculous demand,” said Justin Goodman, a spokesman for Mr. Schumer. “We look forward to organizing the Senate under Democratic control and start getting big, bold things done for the American people.”
But as in past fights over the filibuster, the outcome is likely to be only a temporary solution. As they press forward on Mr. Biden’s agenda, Democrats will come under mounting pressure from activists to jettison the rule, which effectively requires 60 votes to advance any measure, should Republicans use it regularly to stall or stop the administration’s priorities.
Even some lawmakers who have backed the filibuster strongly said they could change their minds if Republicans engaged in constant obstruction.
“I feel pretty damn strongly, but I will also tell you this: I am here to get things done,” said Jon Tester, Democrat of Montana. “If all that happens is filibuster after filibuster, roadblock after roadblock, then my opinion may change.”
Mr. Tester is among those key to the rapidly developing showdown over the fate of the filibuster, the signature feature of the Senate — a once rarely employed weapon now used routinely to stall action in the gridlocked institution — that holds heavy consequences for Mr. Biden’s presidency.
Mr. McConnell’s demand for a pre-emptive surrender on the filibuster had infuriated Democrats who regarded it as evidence that the Republican leader intends to obstruct Mr. Biden’s proposals on pandemic relief, immigration, climate change, health care and more.
“Mitch McConnell will not dictate to the Senate what we should do and how we should proceed,” Mr. Schumer said Sunday. “McConnell is no longer the majority leader.”
The stalemate created a bizarre situation in which most Senate committees were frozen under Republican control and new senators could not be seated on the panels even though Democrats now command the Senate majority.
Beyond the immediate logistical effects, the feud reflected a challenging dynamic in the 50-50 Senate for Mr. Biden. By holding out against Democrats eager to take charge, Mr. McConnell was exercising what leverage he had. But he also foreshadowed an eventual clash in the chamber that might otherwise have taken months to unfold over how aggressive Democrats should be in seeking to accomplish Mr. Biden’s top priorities.
Democrats say they must retain at least the threat that they could one day end the filibuster, arguing that bowing to Mr. McConnell’s demand now would only have emboldened Republicans to deploy it constantly, without fear of retaliation.
“Well that’s a nonstarter because if we gave him that, then the filibuster would be on everything, every day,” Senator Richard J. Durbin of Illinois, the No. 2 Senate Democrat, said Sunday on NBC’s “Meet the Press.”
At issue is a rule that is at the heart of the consensus-driven Senate, which effectively mandates that any legislation draw 60 votes to advance. But like everything else in the chamber, the rule itself is subject to change if senators agree. As the majority party, Democrats could move to eliminate the filibuster and force through a change to the rules on a simple majority vote — a move known as detonating the “nuclear option” — if all 50 of their members held together and Vice President Kamala Harris cast the tiebreaking vote.
As chances rose over the past year that Democrats could win control of the White House and Congress, speculation mounted over whether they would take such action should Republicans dig in against Mr. Biden. But no one anticipated that Mr. McConnell would bring the fight to a boil right from the start by entangling the filibuster in the basic work of setting up the Senate for the next two years through what is known as an organizing resolution, which requires Senate approval.
In calling for the Democratic commitment, Mr. McConnell noted that Democrats relied on the filibuster themselves when Donald J. Trump was president and Republicans held the Senate.
“Democrats used it constantly, as they had every right to,” he said last week on the floor. “They were happy to insist on a 60-vote threshold for practically every measure or bill I took up.”
Mr. Schumer said little of his strategy for rebuffing Mr. McConnell, other than calling his demand unacceptable. The new majority leader seemed to let Democrats and Mr. Biden, a former longtime senator who has been reluctant to overturn the filibuster, simmer over Republican tactics.
Yet Mr. Tester made it clear that Mr. McConnell’s tactics could rapidly change his view of the issue.
“But if, in fact, Mitch is going put up roadblocks and filibuster the organizing resolution, then I think Schumer has to take it to the floor,” Mr. Tester said.
Mr. Manchin had not changed his position even though Mr. McConnell’s demand was preventing Mr. Manchin from taking the helm of a committee of his own. In a 50-50 Senate, his defection alone would prevent the elimination of the rule.
“I’m in the minority of the caucus on this, I’m sure of that,” Mr. Manchin told reporters last week. “I think basically Chuck has the right to do what’s he’s doing. He has the right to use that leverage in whatever he wants to do. I’m not worried about that at all. They will work it out. I just haven’t changed where I’m at.”
Still, Mr. McConnell appeared to have the backing of other Republicans, including moderates who are empowered by the 60-vote requirement, who said they too wanted assurances that Democrats would not upend the filibuster.
“Including some kind of détente on the filibuster is important,” said Senator Lisa Murkowski, Republican of Alaska, who said it was not an issue in 2001 because no one at the time would have contemplated eliminating it. “It was not even a subject that was even thought about, and so it’s a different environment.”
As for Mr. Biden, the White House says his position in support of the filibuster has not changed, though he gave some mixed signals during the campaign. Mr. Schumer and Senate Democrats would be very unlikely to proceed with scrapping the practice without the endorsement of Mr. Biden, particularly because they would need Ms. Harris’s vote to do so.
Mr. Tester said the filibuster had a role to play because it can lead to legislation that can “stand the test of time,” rather than lock Congress in a cycle where one party is always trying to undo partisan legislation passed by the other. But his patience is not infinite.
“I didn’t come here to sit at my desk and wait for no votes to happen,” he said.
Luke Broadwater and Emily Cochrane contributed reporting.