Trump administration officials failed to convince Democratic US lawmakers, and some Republicans, on Wednesday that an imminent threat had justified the killing of a top Iranian military commander, and congressional Democrats scheduled a vote on legislation to rein in the president's ability to wage war.

Secretary of State Mike Pompeo, Secretary of Defense Mark Esper, Joint Chiefs of Staff Chairman Mark Milley and CIA Director Gina Haspel held classified briefings for all 535 members of Congress to discuss President Donald Trump's decision to order a drone strike that killed Qassem Soleimani in Iraq last week.

Following the sessions, most of Trump's fellow Republicans praised the officials, and Trump, for the strike and the presentation. Senator Jim Risch, Republican chairman of the Senate Foreign Relations Committee, said it was one of the best briefings he had ever attended and officials had provided "crystal-clear information."

Underscoring the deep partisan divide in the Capitol, Democrats - and at least two Republicans - said flatly the officials had not provided evidence to back up assertions by Trump and military commanders that Soleimani had posed an "imminent threat" to the United States.

They disputed the administration's argument that the killing of a foreign leader in a third country was legally justified.

US House of Representatives Speaker Nancy Pelosi said shortly afterward that the Democratic-controlled chamber would vote on a war powers resolution as soon as Thursday.

The war powers resolution directs Trump to terminate the use of the US military in or against Iran, unless Congress has declared war or passed an authorization for the use of force against it.

The resolution is expected to easily pass the House, but would face a more difficult time in the Senate, which is controlled by Trump's fellow Republicans.