The US Senate is set to vote on a resolution aimed at curbing President Donald Trump's authority to continue military strikes on Iran, in the first congressional test of support for a war launched without explicit approval from lawmakers.
The bipartisan measure, introduced by Democrat Tim Kaine and Republican Rand Paul, would require the withdrawal of US forces from hostilities against Iran unless Congress authorises the campaign.
The vote on Wednesday comes five days into a rapidly expanding conflict that has already killed Iran's Supreme Leader Ali Khamenei and several senior figures in Tehran, while US troops have died in Iranian strikes and a drone attacks on US bases and consulates in the Gulf.
Democrats argue Trump unconstitutionally bypassed Congress when he ordered the air offensive and say the administration has offered shifting explanations for the war.
"Let me say it this way, there was no presentation of any evidence in that room...that suggested that the US faced any imminent threat from Iran," Kaine said after a classified briefing from administration officials.
Republicans have largely rallied behind their leader, though some have signaled their support could erode if the war expands or drags on.
"Roadside bombs coming out of Iran have maimed and killed hundreds, if not thousands, of Americans," Lindsey Graham, one of Trump's top loyalists in the Senate and a longtime advocate of confronting Iran, posted on X.
'Knocked out'
For the resolution to pass, Democrats would need at least four additional Republicans to join Paul if every senator votes. At least one Democrat, Pennsylvania centrist John Fetterman, has already said he will oppose it.
Others, such as Kentucky Republican Senator Rand Paul, strongly oppose the war. “The constitution conferred the power to declare or initiate war to Congress for a reason, to make war less likely,” Paul said.
“My oath of office is to the constitution, so with studied care, I must oppose another Presidential war.”
Even if the measure cleared both the Senate and the House, where a vote on a similar resolution is expected on Thursday, Trump could veto it, and Congress would need an almost certainly unattainable two-thirds majority in both chambers to override him.
Governments around the world have scrambled to evacuate citizens stranded by the war in the Middle East, triggered by the US-Israeli strikes that killed Khamenei and prompted retaliatory missile and drone attacks across the Gulf.
Cities such as Dubai and Riyadh, long seen as insulated from the region's turmoil, have been drawn into the crisis as the conflict spreads across Iran's neighbourhood.
The debate in Congress over Trump's authority to wage war reflects broader unease on Capitol Hill about the scope and duration of the military offensive.
Administration officials told lawmakers in classified briefings this week that the assault could last weeks and may require additional funding from Congress.
Lawmakers from both parties say the Pentagon could soon seek emergency funds to replenish weapons stockpiles and sustain the offensive.
The War Powers Resolution invokes the 1973 War Powers Act, passed after the Vietnam War, which allows Congress to force votes on military engagements and limits unauthorised conflicts to 60 days.
Democrats acknowledge the measure faces steep odds but say forcing lawmakers to take a public position on the war is essential.
