The U.S. Senate voted 50-48 on Tuesday to approve a concurrent resolution calling on President Donald Trump to halt military operations against Iran or obtain explicit congressional authorization before continuing any further action. The measure had previously passed the House of Representatives earlier this month by a vote of 215-208, marking the first time both chambers of Congress have approved a war powers resolution instructing a president to end a military action since the War Powers Resolution of 1973 was enacted.

Four Republican senators broke with their party to support the measure: Rand Paul of Kentucky, Lisa Murkowski of Alaska, Susan Collins of Maine, and Bill Cassidy of Louisiana. Democratic Sen. John Fetterman of Pennsylvania was the only member of his party to vote against it. Republican Sens. Mitch McConnell of Kentucky, who was hospitalized earlier this month, and Dave McCormick of Pennsylvania did not vote; White House officials noted that had both been present and voted in opposition, the resolution would have failed on a 50-50 tie.

Because the measure was introduced as a concurrent resolution rather than a joint resolution, it does not go to the president's desk for signature and carries no force of law. A White House official dismissed the vote as having "no significance" and argued it was moot in any case, saying hostilities had already ended with a ceasefire agreed on April 7. Trump responded on his Truth Social platform, calling the vote "poorly timed and meaningless" and referring to the four dissenting Republicans as "losers" who had provided "aid and comfort" to the enemy.

The United States entered the current conflict on February 28, when Trump joined Israel in launching strikes against Iran, triggering a broader regional war now approaching its fifth month. The conflict follows a separate episode in June 2025, known as the Twelve-Day War, in which Trump ordered bombers to strike three Iranian nuclear enrichment sites. Trump has maintained the military campaign is necessary to prevent Iran from developing a nuclear weapon, a stated goal Iran has denied pursuing.

Negotiations over the terms of a June 17 memorandum of understanding between the U.S. and Iran are ongoing in Switzerland, though the agreement's durability remains uncertain. Israel has continued to conduct strikes in Lebanon in apparent violation of the accord's terms, which called for a halt to fighting across all fronts. The Senate vote adds symbolic pressure on the White House ahead of November midterm elections, which will determine whether Republicans can maintain their slim majorities in both chambers of Congress.