The US Senate on Tuesday moved forward with a resolution aimed at limiting President Donald Trump’s authority to continue military action against Iran without approval from Congress, marking a rare challenge to the Republican president nearly three months after U.S. and Israeli strikes on Iran began.
Lawmakers voted 50-47 to advance the measure, with four Republicans joining nearly all Democrats in support.
Three Republican senators were absent during the vote.
The resolution, introduced by Democratic Senator Tim Kaine, argues that Congress not the president has the constitutional power to authorize war.
While the vote was seen as a symbolic victory for lawmakers pushing back against executive war powers, the measure still faces major obstacles before it can become law.
Even if it clears the Senate, it must still pass through the Republican-controlled House of Representatives. It would also need enough support to overcome an expected veto from Trump, requiring a two-thirds majority in both chambers.
Speaking before the vote, Kaine said the current ceasefire between Iran and the U.S.-Israeli coalition was the right moment for Congress to debate America’s role in the conflict.
“This is exactly the time Congress should be involved before another war begins,” Kaine said, accusing the administration of dismissing diplomatic proposals from Tehran without consulting lawmakers.
Republicans had previously blocked seven similar attempts in the Senate this year, while House Republicans also shut down three related measures.
Pennsylvania Senator John Fetterman was the only Democrat to oppose the resolution. Republican senators Rand Paul, Susan Collins, Lisa Murkowski, and Bill Cassidy voted alongside Democrats in support.
Cassidy’s vote drew attention after he recently lost his primary election to a Trump-backed challenger.
The debate comes after the expiration of a 60-day window under the 1973 War Powers Act, which limits how long a president can engage U.S. forces in military action without congressional approval.
The law was created after the Vietnam War to prevent prolonged military conflicts without oversight from Congress.
Although Trump declared on May 1 that hostilities with Iran had effectively ended following a ceasefire, tensions have remained high.
The U.S. has continued operations targeting Iranian shipping, while Iran has maintained pressure in the Strait of Hormuz and launched attacks on American vessels.
Democrats and a small group of Republicans argue that the president has pushed the country deeper into conflict without clearly outlining long-term goals or seeking formal authorization from Congress.
The White House and Republican allies, however, insist Trump acted within his authority as commander-in-chief, saying the military actions were necessary to protect U.S. interests and security.
