The Senate voted 50-47 on Tuesday to advance a resolution that would force President Donald Trump to end U.S. military operations in Iran, marking a breakthrough for the Democratic-led effort to constrain executive war powers. The procedural vote moves the measure closer to a final floor vote.
Sen. Bill Cassidy, R-La., who lost his primary for renomination over the weekend after facing opposition from Trump, voted "yes" to advance the measure — the first time he has supported it after repeatedly opposing similar attempts. His flip adds a fifth Republican senator to the coalition backing the war powers resolution.
What the Left Is Saying
Senate Minority Leader Chuck Schumer, D-N.Y., celebrated the vote as evidence that Democratic pressure was working. "Vote by vote, Democrats are breaking through Republicans' wall of silence on Trump's illegal war," Schumer said in a statement. "For more than 80 days, Trump has dragged America into a costly, chaotic conflict with no plan, no objective, and no legal authority. Today proved our pressure is working: Republicans are starting to crack, and momentum is building to check him. We are not letting up."
Sen. Tim Kaine, D-Va., the sponsor of the resolution, has argued that any military engagement requires explicit congressional authorization under the Constitution. "Congress hereby directs the President to remove the United States Armed Forces from hostilities within or against Iran, unless explicitly authorized by a declaration of war or a specific authorization for use of military force," the resolution states.
What the Right Is Saying
Cassidy defended his decision while affirming support for the administration's broader goal of dismantling Iran's nuclear program. "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 in a statement. "In Louisiana, I've heard from people, including President Trump's supporters, who are concerned about this war. Until the administration provides clarity, no congressional authorization or extension can be justified."
Other Republicans who crossed party lines — Rand Paul of Kentucky, Lisa Murkowski of Alaska, and Susan Collins of Maine — have supported similar measures in the past. The three absent senators — John Cornyn of Texas, Thom Tillis of North Carolina, and Tommy Tuberville of Alabama — could shift the outcome if they return and vote against the measure.
What the Numbers Show
Tuesday's procedural vote: 50-47 in favor of advancing the resolution. Five Republicans joined all Democrats except Sen. John Fetterman of Pennsylvania, who has opposed the resolution at every stage. The final vote count would need to reach a simple majority to pass the Senate. With three Republicans absent, a 50-50 tie would defeat the measure.
The resolution has been stalled for more than 80 days during which U.S. forces have been engaged in operations against Iran without explicit congressional authorization, according to statements from Democratic leaders. Trump won the 2024 presidential election and took office in January 2025.
The Bottom Line
While Tuesday's vote represents a procedural step forward, the resolution still faces significant obstacles. It would need to pass the full Senate, survive a likely presidential veto, and clear the Republican-controlled House of Representatives — where leadership has shown little appetite for constraining Trump's foreign policy authority. The outcome may hinge on whether absent senators return and how wavering Republicans ultimately position themselves.
What to watch: Whether additional Republican senators announce support ahead of a final vote, how the White House responds to congressional pressure, and whether the House takes up any version of the resolution.