Cassidy breaks with Trump on Iran war powers vote after primary loss: ‘Congress left in the dark’
WASHINGTON, DC: The Senate on Tuesday, May 19, voted 50-47 to advance a war powers resolution aimed at forcing President Donald Trump to end US military involvement in Iran unless Congress authorizes the conflict.
The procedural vote marked the first time the chamber has moved the measure forward after seven failed attempts since the war began in February.
The breakthrough came after Republican Senator Bill Cassidy of Louisiana switched his position and voted in favor of advancing the resolution following his primary election defeat.
The resolution, introduced by Senator Tim Kaine, directs the president to remove US armed forces from hostilities involving Iran unless Congress passes a declaration of war.
Bill Cassidy flips on Iran war powers vote
Cassidy’s vote proved crucial in advancing the Democratic-led effort after he had repeatedly opposed similar measures in earlier votes. The Louisiana senator recently lost his Republican primary after facing opposition from Trump, who backed his challenger.
In a statement following the vote, Cassidy said, “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."
"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.”
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. In Louisiana, I’ve heard from people, including President Trump’s supporters, who are concerned about this war.…
— U.S. Senator Bill Cassidy, M.D. (@SenBillCassidy) May 19, 2026
Three other Republican senators, Rand Paul, Lisa Murkowski, and Susan Collins, also voted with Democrats to advance the measure, as they had done previously. Every Democrat supported the procedural motion except Senator John Fetterman, who again voted against it.
🇺🇸🇮🇷 US Senate advances WAR POWERS VOTE requiring congressional approval for Iran military campaign
— Donald J Trump Truth Social Posts On X (@TrumpTruthOnX) May 19, 2026
First successful Senate vote after seven failed attempts — direct challenge to Trump's executive war authority pic.twitter.com/aZToNPKFrg
Meanwhile, three other Republican senators, John Cornyn, Thom Tillis, and Tommy Tuberville, were absent during the vote, leaving uncertainty over whether the resolution will ultimately pass when brought up for final approval.
Democrats challenge Trump’s Iran war authority
Democrats framed the vote as a sign of growing bipartisan concern over the administration’s handling of the conflict and Congress’ limited role in authorizing military action.
“Vote by vote, Democrats are breaking through Republicans’ wall of silence on Trump’s illegal war,” Senate Minority Leader Chuck Schumer said after the vote.
“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.”
Ahead of the vote, Kaine argued lawmakers should debate the long-term implications of the military campaign.
“The Senate should use this moment to do what we should have done before the war started, discuss the rationale, strategy, end state, and costs to American taxpayers and our economy,” he said.
Although the resolution has now advanced in the Senate, it would still need approval in the Republican-controlled House of Representatives and would almost certainly face a presidential veto if it reaches Trump’s desk.
