WASHINGTON, May 19, 2026 — After seven consecutive failures, the U.S. Senate on Tuesday advanced a war powers resolution to restrict President Donald Trump’s military campaign in Iran, passing a procedural vote 50-47 that marked the first breakthrough of its kind since the conflict began in late February. The outcome was made possible by four Republican senators — Rand Paul of Kentucky, Susan Collins of Maine, Lisa Murkowski of Alaska, and Bill Cassidy of Louisiana — who joined nearly all Democrats in voting to discharge the measure from committee and send it toward a floor vote. Three other Republicans who had previously voted against such resolutions — John Cornyn of Texas, Tommy Tuberville of Alabama, and Thom Tillis of North Carolina — were absent, a convergence of defections and absences that finally tipped the count in Democrats’ favor.
The resolution, brought under the 1973 War Powers Act, would direct Trump to withdraw U.S. armed forces from hostilities against Iran unless Congress formally authorizes continued military action. The conflict began February 28, when the Trump administration launched strikes on Iran without seeking congressional approval. Since then, Democrats have forced the Senate to vote on the matter eight times, all of them failing until Tuesday.
Rand Paul: A Constitutional Argument, Vote After Vote
Of the four Republicans, Paul has been the most consistent dissenter. The libertarian-leaning senator from Kentucky voted in favor of every single one of the eight attempts, making him the only Republican to support the measure from the very beginning of the conflict.
“Only Congress can declare war,” Paul said after the first failed vote. “That’s not my opinion. That’s Article 1 of the Constitution. We forced the vote. The Senate said ‘no.’ History will not be kind to a Congress that gave away its most solemn responsibility.”
Paul framed the resolution as a matter of constitutional separation of powers. “The constitutional separation of war powers is not just some notion that belongs in our history books,” he wrote in a Fox News column. “It’s a vital part of a democratic republic. This Congress should be ashamed of how it has allowed this unilateral march to war.”
Paul was also candid about the financial toll. He told reporters that he was “not for adding more debt” and believed that adding more made the country “less safe,” adding that “the war should come to a conclusion as soon as possible.” He was equally blunt about the public’s lack of information going into the conflict. “Americans were not asked if they would bear the burdens of war,” he said. “Instead, the American people were told, through a presidential eight-minute video posted around 2:30 in the morning, that the country was, once again, at war.”
Trump publicly lashed out at Paul over his repeated support for the resolutions. The president warned that lawmakers who don’t “stick together” would “hopefully someday be gone,” and told Paul directly: “Vote for us, and don’t call me great. I’d rather have the vote, than the statement.” Paul did not relent.
Susan Collins: A Late but Firm Conversion
Collins, the moderate Maine Republican, voted against the first several war powers resolutions before breaking with her leadership for the first time on April 30 — the 59th day of hostilities, one day before the War Powers Act’s 60-day deadline for congressional authorization.
In a statement explaining her vote, Collins cited the Constitution directly. “The Constitution gives Congress an essential role in decisions of war and peace, and the War Powers Act establishes a clear 60-day deadline for Congress to either authorize or end U.S. involvement in foreign hostilities,” she said. “Further military action against Iran must have a clear mission, achievable goals, and a defined strategy for bringing the conflict to a close. I voted to end the continuation of these military hostilities at this time until such a case is made.”
Collins had earlier explained her reluctance to break with the administration in the early weeks of the war. At the time she had argued that “passing this resolution now would send the wrong message to Iran and to our troops,” and that “providing unequivocal support to our service members is critically important, as is ongoing consultation by the Administration with Congress.” Once the 60-day deadline passed, however, she concluded that the legal threshold had been crossed and voted consistently for the resolution through its final successful advancement on Tuesday.
Lisa Murkowski: Crossing Over After the Deadline
Murkowski, the Alaska Republican, voted against the war powers measure through the first six attempts before switching sides on May 13 — the seventh vote, and the first since the statutory 60-day limit expired. Her flip made that vote a 49-50 near-miss, the closest the measure had come to passing before Tuesday.
In her statement, Murkowski cited two factors that had changed since her earlier opposition: “We have now surpassed the 60-day limit for hostilities without congressional authorization, and the administration has asserted that hostilities have ended, despite the blockade and continued fire directed at members of the U.S. Armed Forces, as well as our assets, allies, and partners.”
Her decision came shortly after a tense exchange with Defense Secretary Pete Hegseth, who told her during a congressional hearing that the Trump administration believed it had “all the authorities necessary” to resume strikes on Iran without congressional approval. Murkowski voiced open skepticism, pointing to the troops and warships still deployed to the region and saying, “It doesn’t appear that hostilities have ended.”
Bill Cassidy: Nothing Left to Lose
The most dramatic vote of the four came from Cassidy, who had opposed every previous war powers resolution — until Tuesday. Three days earlier, on May 16, Cassidy lost his Louisiana Senate primary after Trump endorsed Rep. Julia Letlow, one of his challengers. Cassidy was one of seven Republican senators who voted to convict Trump following the January 6 Capitol attack, a vote that many Louisiana primary voters described as a betrayal. Trump endorsed Letlow in January, and her campaign repeatedly labeled Cassidy a “never Trumper” in television ads.
Cassidy’s defeat made him the first Republican senator Trump successfully ousted. He returned to Washington defiant. After the primary loss, Cassidy said he was proud of his work to uphold the Constitution and would carefully consider how he voted on several Trump administration priorities going forward. On Tuesday, that consideration yielded a new position. “While I support the administration’s efforts to dismantle Iran’s nuclear program, the White House and Pentagon have left Congress in the dark on Operation Epic Fury,” Cassidy said on social media.
Absences That Mattered
The resolution’s success on Tuesday was also shaped by who was not in the chamber. Senators John Cornyn of Texas, Thom Tillis of North Carolina, and Tommy Tuberville of Alabama — three Republicans who had previously opposed taking up war powers resolutions on Iran — all missed the vote. Had all three voted against it, the resolution would have failed 50-50.
The road ahead remains uncertain. The measure would still need to pass the House, which narrowly rejected a similar resolution the week prior, and Trump would almost certainly veto it — forcing a two-thirds supermajority override that no war powers resolution has ever achieved. Senate Minority Leader Chuck Schumer struck a defiant tone regardless. “Vote by vote, Democrats are breaking through Republicans’ wall of silence on Trump’s illegal war,” Schumer said. “Today proved our pressure is working: Republicans are starting to crack, and momentum is building to check him. We are not letting up.”