WASHINGTON — The Senate voted on Wednesday to repeal authorizations from 1991 and 2002 for combat operations against Iraq, moving with broad bipartisan support to advance a yearslong effort to claw back congressional war powers.
The bill goes next to the Republican-led House, which has passed similar legislation several times in recent years but where G.O.P. leaders are undecided about whether to put it on the floor. Still, the 66-to-30 vote in the Senate was a potentially pivotal step in the long-running push by Republicans and Democrats to reassert the national security prerogatives of Congress, with 18 G.O.P. senators joining in support.
It reflected a belief among a growing number of lawmakers in both parties that it is long past time for the legislative branch to play its constitutional role as a check on an executive branch that has embroiled the country in endless wars.
“Congress has abdicated its powers to the executive for too long,” said Senator Tim Kaine, Democrat of Virginia and the chief author of the Senate’s efforts to repeal the Iraq war authorizations for the past several years. “Presidents can do mischief if there are outdated authorizations on the books.”
Should the measure clear Congress and be signed by President Biden, who has indicated his support, it would be the first repeal of a war authorization in more than a half century. It would also be a crucial first step toward building momentum to tackle more significant and far more complicated endeavors. Those include replacing the authorization Congress passed in 2001 to start military operations against terrorist groups in Afghanistan after the Sept. 11 terrorist attacks. That authorization stretched across four administrations to permit open-ended combat against Islamist militant groups around the world and ultimately rewrote the law defining the president’s war powers.
“We’re closer now than we’ve ever been,” Mr. Kaine said. “If we get this first one done, I’m going to take a day off, and then I’m going to start working on the others again.”
While his limitless optimism for repealing war authorizations has often seemed out of step with its prospects for success, this year there is reason to believe things might be different. For the first time in two decades, the House and the Senate are pursuing identical legislation, and backers have assembled what they call a “trans-partisan” coalition comprising majorities in both chambers to back them.
“We have the momentum,” said Representative Tom Cole of Oklahoma, the Republican chairman of the House Rules Committee. “People are clearly breaking our way.”
Mr. Cole is a chief Republican sponsor of this year’s Iraq-focused effort, alongside Representatives Barbara Lee, Democrat of California; Abigail Spanberger, Democrat of Virginia; and Chip Roy, Republican of Texas.
“Look, if you’ve got Chip Roy and I both co-sponsoring the same bill, then surely you’ve got the whole spectrum of the Republican Party,” Mr. Cole added.
Mr. Cole, an old-guard conservative, and Mr. Roy, a firebrand member of the right-wing Freedom Caucus, represent factions of the party that have clashed over everything from funding the war in Ukraine to selecting Speaker Kevin McCarthy of California as their leader. But both have a track record of supporting efforts to repeal the Iraq-focused authorizations for the use of military force, known as A.U.M.F.s.
Mr. Roy has been voting for them since July 2019, when only 14 Republicans backed repealing the 2002 measure as an amendment to the House’s annual defense bill. Mr. Cole has been on board since 2021, when 49 Republicans voted for stand-alone repeals of both.
Over the past few years, there has also been a pronounced generational shift in Congress and in both parties, where antiwar voices on the left have aligned with “America First” enthusiasts on the right who resist entangling the United States in foreign conflicts. Only 69 lawmakers remain in Congress who cast a vote for the 2002 Iraq war authorization, when about half of them supported it. Of those 69, only 17 oppose repealing the measure today. At the same time, many of the new entrants have brought different attitudes to Washington about how Congress should approach matters of war and peace.
“Twenty years gives time for people to change their minds and think about things and evaluate them, and so I think that’s all part of it,” said Senator Bob Menendez, Democrat of New Jersey and the chairman of the Foreign Relations Committee. “It’s reasonable to think that this has the ability to make it all the way.”
Yet the road through the Republican-led House may depend chiefly on whether party leaders who have historically opposed repealing such measures are willing to relent — and those leaders are presently under tremendous pressure to stop the bill in its tracks.
“I hope Kevin McCarthy will take up this cause,” said Senator Lindsey Graham, Republican of South Carolina, who has opposed the repeal effort.
Republican senators wary of repeal rallied around a series of amendments over the past week that would have undercut the effort, including proposals to make the rollback contingent on eliminating threats from Iranian-backed groups in Iraq. Their cause found new inspiration last week, after a drone of “Iranian origin” killed a U.S. contractor and wounded five American service members in Syria.
Republican lawmakers accused the Biden administration, which has signaled its support for repealing the Iraq war authorizations, of trying to cover up the episode for several hours to deprive them of potential amendment votes on the floor.
“That is absolutely not true,” Defense Secretary Lloyd J. Austin III told Senator Tom Cotton, Republican of Arkansas, during a hearing on Tuesday, after the senator leveled the charge.
So far, Mr. McCarthy has not signaled that his stance on repealing the Iraq war resolutions would be swayed by the Syria strike. He told reporters this month that so long as the 2001 resolution for the war on terror was kept in place, repealing the measure on Iraq was “personally where I believe I am.”
Representative Mike D. Rogers, Republican of Alabama and the chairman of the Armed Services Committee, suggested that repealing the Iraq-focused authorization was essentially meaningless. “I don’t really care” whether it happens, he said in an interview.
That would leave Representative Michael McCaul, Republican of Texas and the chairman of the Foreign Affairs Committee, as potentially the biggest obstacle to repealing the resolutions. Mr. McCaul, who has vocally opposed rolling them back in the past, has written a draft bill to replace the 2002 authorization rather than replacing it, but he declined to detail how it would work and said he was uncertain whether other leading Republicans would go along with it.
“I’m still waiting to hear back from leadership on if we can go forward with a replacement, and if not, I’m sure it probably has the votes to pass,” he said of the repeal.
Mr. McCaul’s admission shows a major shift in how attitudes toward war authorizations have changed since Congress passed the 2001 and 2002 measures, with most of the change happening in the past couple years.
For years before Mr. Kaine came to Congress, the chief engine of repeal efforts was Ms. Lee, who was known for being the only lawmaker to vote against authorizing both the Iraq and Afghanistan wars. She partnered with Representative Walter B. Jones, Republican of North Carolina, to try to put limits on the president’s war-making powers, but the two struggled to build support amid active conflicts.
That resistance persisted in the Senate as well, even after Mr. Kaine took up the cause and enlisted Senator John McCain, Republican of Arizona, a former prisoner of war and hawk who agreed that Congress had to reassert its war powers, and secured a passive go-ahead from the Obama administration. Mr. Kaine would go through a series of Republican dance partners but never managed to secure so much as a committee vote.
It was not until Mr. Kaine joined forces with Senator Todd Young, Republican of Indiana — and a new crop of House lawmakers, many of whom had served in the Iraq and Afghanistan wars, came to town — that the playbook markedly changed.
“When I picked this up, there was not a ’91 and ’02 repeal effort underway,” Mr. Young said in an interview, recalling how he and Mr. Kaine had decided to table the “more challenging” task of rewriting the 2001 resolution until they could soften the ground by dealing with the Iraq-related measures. “This is what made sense, to try and earn some trust back from the American people.”
Months later, the Trump administration cited the 2002 authorization as part of its legal justification for killing Maj. Gen. Qassim Suleimani, the Iranian security and intelligence commander, in a drone strike near the Baghdad airport in January 2020.
That was a breaking point for some lawmakers who had already grown disillusioned with what they saw as a pattern of executive overreach on national security matters, such as the Obama administration’s military interventions in Libya and Syria and the Trump administration’s efforts to supply the Saudi-led war in Yemen and end-run Congress on related weapons sales.
“It was like, ‘Really?’” Mr. Cole said in an interview. But he conceded that the bulk of the Republican skeptics, including himself, were reluctant to vote to repeal any war powers measures until President Donald J. Trump had left office.
“It’s easier when it’s not your person in the White House,” Mr. Cole said. “No question.”