The US Senate passed a procedural resolution requiring President Donald Trump to obtain congressional approval for any military action against Iran. The vote took place on May 19: 50 senators voted in favor — mostly Democrats and four Republicans, while 47 voted against, and three additional Republicans were absent.
This marks the first success after eight attempts. All previous similar resolutions had been blocked by Republicans in the Senate; in the House of Representatives, three more resolutions also failed this year.
The authors of the initiative invoke the Constitution: the right to declare war belongs to Congress, not the president. If the resolution is ultimately adopted, Trump will need lawmakers’ authorization to continue the war against Iran.
The path forward for the document, however, is far from over. In addition to a final Senate vote, it must pass through the House of Representatives, where Republicans hold the majority. To override Trump’s expected veto, two-thirds of votes in each chamber would be required.
The background to this issue dates back to June 2025, when the United States struck Iranian nuclear facilities. The Senate then considered a war powers bill for the first time. A second vote was held on March 5, 2026, shortly after the start of the joint US-Israeli military campaign against Iran.
Under the US War Powers Act of 1973, the president may conduct military operations for up to 60 days without congressional approval. That deadline expired on May 1. On the same day, Trump declared that a temporary ceasefire with Iran had “put an end” to hostilities.
