This is reported by Reuters.
The vote on the procedural measure, which is held before the main vote, was held on May 19. “For” voted 50 senators (mostly Democrats and four Republicans), against 47 (mostly Republicans and one Democrat). Three Republicans skipped the vote.
The initiative’s sponsors insist that under the Constitution, the power to send troops to war belongs to Congress, not the president. If the document passes a further vote, Trump will need congressional authorization to go to war with Iran.
As Reuters notes, in addition to the main Senate vote, the resolution must pass through the House of Representatives, which is controlled by Republicans, and receive a two-thirds vote in both the House and Senate to override Trump’s expected veto.
Republican representatives have blocked seven previous attempts to advance similar resolutions in the Senate. They have also failed three war powers resolutions in the House this year.
The Senate first considered a war powers bill in 2025 after the U.S. struck Iran’s nuclear facilities in June. The second vote was held already this year, on March 5, shortly after the U.S. and Israel went to war with Iran.
Under the U.S. War Powers Act of 1973, the president can conduct military action for 60 days, after which he must either end it, get congressional authorization or get a 30-day extension. The 60-day period expired on May 1. That same day, Trump announced that a temporary truce with Iran had “ended” military action.
