A bipartisan group of senators on Thursday unveiled the most sweeping rewrite of the War Powers Resolution in more than five decades, arguing that the seven-week Iran conflict exposed gaps in congressional oversight that lawmakers can no longer afford to ignore.

The Authorization and Reporting Clarity Act, introduced by Sens. Tim Kaine, D-Va., Mike Lee, R-Utah, Chris Murphy, D-Conn., and Todd Young, R-Ind., would shorten the window for unauthorized military engagement from 60 days to 20, require the president to submit a written legal justification within 48 hours of any kinetic action, and automatically sunset prior authorizations for the use of military force after eight years unless Congress votes to extend them.

“This is the bill we should have passed twenty years ago, and the Iran war is the reason we cannot wait any longer,” Kaine said at a Capitol news conference, flanked by his three co-sponsors. “American service members are owed a Congress that votes on the wars they fight.”

The legislation arrived three weeks after the April 15 ceasefire between Iran, Israel and the United States took effect, and one day after the Defense Department finalized its preliminary casualty accounting at 358 American military deaths from the conflict, the highest single-engagement toll in more than a generation.

White House press secretary Marlena Cortez declined to take a position on the bill Thursday but signaled the administration’s resistance to any measure that would, in her phrasing, “tie the commander in chief’s hands while the country is still reckoning with the threats that started this war.” President Donald Trump, asked about the proposal as he departed the South Lawn for an event in Pennsylvania, called the senators “well-meaning but naive” and said that “you cannot run a war by committee, and you can’t run a peace by committee either.”

The bill’s sponsors said they expected the administration to oppose the measure but contended that the political environment had shifted decisively since the ceasefire. A Pew Research Center survey released Tuesday found that 64 percent of Americans believed Congress should have voted on the Iran engagement before U.S. forces conducted strikes, up from 41 percent in a comparable February poll. Forty-eight percent of self-identified Republicans now support a formal congressional vote on any future military action of more than two weeks’ duration, a 17-point increase from a year ago.

“The numbers are unusual, and they’re durable,” said Eliza Tarrant, a senior fellow at the Bipartisan Policy Center who has studied war powers polling for more than a decade. “What you’re seeing is a coalition that includes libertarian-leaning Republicans, progressive Democrats and a meaningful slice of independents who watched the casualty figures climb in March and concluded that the existing system isn’t working.”

Murphy, who led the Senate Foreign Relations subcommittee that took classified briefings on the Iran engagement in March and April, said the bill’s 20-day window was chosen deliberately. “If the country is going to commit to a war that lasts longer than three weeks, the American people deserve to hear their representatives debate it on the floor,” he said. “That is not a radical idea. It is the constitutional baseline.”

Lee, a longtime critic of expansive executive war-making authority, said he had spent recent weeks lobbying colleagues in his own conference and described private conversations with “more than a dozen” Republican senators who he said were sympathetic to the measure but had not yet committed to voting for it. He declined to name them.

The bill also includes a provision, drafted in consultation with the Congressional Research Service, that would require the president to specify the legal authority under which any operation is conducted, rather than relying on layered citations to prior authorizations such as the 2001 and 2002 measures that have underpinned operations in more than a dozen countries.

Speaker Mike Johnson’s office said the House had no immediate plans to take up companion legislation, though Rep. Warren Davidson, R-Ohio, and Rep. Sara Jacobs, D-Calif., are expected to introduce a parallel bill in the House next week. A senior House Republican aide, who spoke on condition of anonymity to discuss internal deliberations, said the conference was “split three ways” between members aligned with the administration, members aligned with the bill’s premise, and members who wanted to wait for the formal Pentagon after-action review expected in late June.

Sen. Tom Cotton, R-Ark., a frequent critic of Kaine-led war powers efforts, dismissed the new bill in a statement Thursday afternoon as “another attempt to convert tactical patience into strategic paralysis.” Senate Majority Leader John Thune has not yet committed to floor time, though he told reporters Thursday that the proposal was “serious and deserving of serious consideration.”

The legislation lands amid a broader recalibration of post-war oversight on Capitol Hill. The Senate Armed Services Committee opened closed hearings this week on the use of pre-positioned munitions during the conflict, and the House Foreign Affairs Committee has scheduled testimony for May 14 from former diplomats involved in the Islamabad track that produced the April 12 framework.

Young, the only sponsor up for re-election in 2026, said the bill was not a referendum on the Trump administration’s handling of the war. “This is about the next war, and the war after that,” he said. “We are writing the rules for a future president, and that president could be from either party.”

The sponsors said they would seek a committee markup before the Memorial Day recess and would push for floor consideration in June. Aides said additional cosponsors would be announced in the coming days.