The US House of Representatives has passed a resolution seeking to stop Donald Trump from taking further military action against Iran.
The Democratic-controlled House voted 224 to 194, mostly along party lines, sending the war powers resolution to the Senate.
It comes days after the US leader ordered a drone strike that killed a top Iranian commander Qassem Soleimani and raised fears of war.
The result reflected the deep divide in Congress over Mr Trump's Iran policy and how much of a say lawmakers should have over the use of the military.
Democrats accused Mr Trump of acting recklessly and backed the resolution, while Mr Trump's fellow Republicans opposed it.
"The president has to make the case first, first, not after he launches an ill-advised attack and then comes up with a reason why it was necessary and why it was legal," said Representative Eliot Engel, chairman of the House Foreign Affairs Committee.
Republicans said Democrats endangered the country by trying to pass a resolution they characterised as an empty political gesture.
"Instead of supporting the president, my Democrat colleagues are dividing Americans at a critical time," said Representative Mike McCaul.
The ranking Republican on the foreign affairs said the resolution would "tie the president's hands."
The fate of the resolution is uncertain in the Senate.
Republicans hold 53 of the chamber's 100 seats and rarely vote against the president.
But at least two Republican senators - Rand Paul and Mike Lee - have expressed support for the measure.
If passed by the House and Senate, the measure does not need Mr Trump's signature to go into effect.
However, Democrats and Republicans disagreed over whether it was binding.
Democratic House Speaker Nancy Pelosi faulted the White House for failing to consult Congress before the drone strike that killed Soleimani in Baghdad.
"Last week, in our view, the president - the administration - conducted a provocative, disproportionate attack against Iran, which endangered Americans," Pelosi told a news conference.
The War Powers Act, which was passed in 1973 as Congress reacted to secret bombings during the bitterly divisive Vietnam War, says the House and Senate can pass a resolution to force the withdrawal of troops engaged in a foreign conflict without Congress' consent.
It was not immediately clear what would follow if the resolution passes the Senate.
Legal questions about Congress' power over the president's role as commander-in-chief are unresolved.
