The US House of Representatives has passed a measure that seeks to halt President Donald Trump from taking further military action in Iran.
The 215-208 vote, which is largely symbolic, was successful after four Republicans joined Democrats in a public show of disapproval of the war, which began in February.
The vote was to adopt the war powers resolution, which requires Trump to withdraw US forces or seek congressional approval for the conflict.
It is unclear how much legal force this House measure would have. The White House has dismissed the merits of the resolution, saying it is an unconstitutional attempt to restrict presidential power.
But its passing is significant because it adds to the pressure on the White House to find an end to the Iran War, as petrol prices have spiked and public opposition to the war has increased.
This was the fourth attempt by the House to rein in Trump's war powers. The Senate advanced a similar resolution in May but has yet to hold a full floor vote.
The measure considered on Wednesday was a concurrent resolution. If it is also passed by the Republican-controlled US Senate, it would not require the president's signature, though it could be subject to a legal challenge.
The vote on Wednesday marked the latest sign of division within Trump's Republican Party, coming just days after a revolt by conservatives in Congress led his administration to pull back plans for a $1.8b "anti-weaponization" fund for political allies.
In the House, Republicans Thomas Massie, Brian Fitzpatrick, Tom Barrett, and Warren Davidson joined a united front from Democrats to pass Wednesday's resolution. Democrat Jared Golden of Maine, who had previously voted against similar measures, gave his support this time.
"Congress alone declares war, that's something certainly we need to be protective of," Barrett, a Republican from Michigan, said. Asked if he was worried about retribution from Trump for his vote, Barrett said: "I vote my conscience for what I think is right and willing to accept that."
Representative Gregory Meeks, the leading Democrat on the House Foreign Affairs committee, described the vote as "a significant bipartisan rebuke of President Trump's illegal and costly war in Iran and the first step toward ending it once and for all".
Meeks said that Trump had failed to achieve the war's stated aims while pushing up fuel prices at home and making a diplomatic solution to Iran's nuclear programme even more difficult to achieve.
"The passage of this [measure] today signals a significant turning point: more and more Republicans are listening to their constituents who do not want another open-ended war in the Middle East," Meeks, who co-sponsored the resolution, said.
The US and Israel launched strikes against Iran on 28 February. Iran responded by attacking Israel and US-allied states in the Gulf, and effectively closed the Strait of Hormuz, a vital waterway for global shipping.
In April, the US announced it would impose a blockade on ships travelling to or from Iran's coast.
The US and Iran reached an initial ceasefire agreement on 8 April.
Despite that agreement, the US has struck Iran in recent days, with Tehran responding with strikes on Kuwait, a US ally. Ahead of the vote, Trump again asserted that negotiations to end the war are going "very well" and could be finalised as soon as this weekend.
"We hit them pretty hard the night before, and actually last night," Trump told reporters at the White House on Wednesday, referring to strikes in Iran. "Some people would say they were slightly provoked because we took a strong action for a different reason, so they were reciprocating."
The president added that most of the members of his administration are hoping to end the conflict soon with a deal "without killing everybody".
"In theory they're pretty close to signing a paper, we've actually gotten along with them very well."
