WASHINGTON — The House took a preliminary vote on Thursday to advance a measure that would force President Trump to go to Congress for authorization before taking further military action against Iran, reigniting a fierce and longstanding debate over the role of the legislative branch in waging war.
The 226-to-193 procedural vote, split almost entirely along party lines, comes as Democrats — joined by two Republican senators — have raised questions about Mr. Trump’s rationale and justification for ordering the drone strike last week that killed Maj. Gen. Qassim Suleimani.
It paved the way for the Democratic-led House to hold a final vote later Thursday to approve the War Powers Resolution, after a debate that pitted presidential power against congressional prerogatives.
“We have seen that developments can change day by day, hour by hour,” said Representative Jim McGovern, Democrat of Massachusetts. “Should tensions escalate again, Congress should have a say before hostilities are launched. It is really that simple.”
Lawmakers were rankled by the White House’s failure to confer with Congress before the strike, and were dissatisfied with the classified notification the administration sent to Capitol Hill afterward. And they left their first briefings on the matter on Wednesday, with Mr. Trump’s national security team, irate.
Citing the mercurial nature of the president’s foreign policy and what they said was a dearth of credible information presented by administration officials to Congress justifying the strike, Democrats lined up on the House floor to argue that the week of escalating tensions underscored Congress’s duty to reclaim its constitutional authority to declare war.
“We should not be going to war in the name of the United States based on the word of one man,” said Representative Jamie Raskin, Democrat of Maryland. “That’s not the constitutional design.”
Still, the House measure — sponsored by Representative Elissa Slotkin, Democrat of Michigan and a former C.I.A. and Pentagon analyst specializing in Shiite militias — could amount to little more than a statement of principle, without the force of law.
House Democrats opted to use a concurrent resolution — the type that is considered to be enacted once both chambers approve it and is never presented to the president for his signature — rather than a joint resolution, which Mr. Trump could veto.
“This is a statement of the Congress of the United States,” Ms. Pelosi said Thursday at a news conference, “and I will not have that statement be diminished by whether the president will veto it or not.”
The Supreme Court ruled in 1983 that to have legal effect, an action of Congress must be presented to the president for signature or veto. But Ms. Pelosi insisted on Thursday, without elaborating, that the House measure would have legal teeth.
At least one Democrat, Representative Max Rose of New York, an Army combat veteran, said he would oppose the resolution on Thursday, dismissing it as a symbolic measure.
“Today’s War Powers Resolution is a nonbinding resolution that simply restates existing law and sends the message that war is imminent,” Mr. Rose said in a statement. “I refuse to play politics with questions of war and peace, and therefore will not support this resolution.”
Most Republicans, who are often reluctant to criticize the president, especially on matters of national security, have stood in lock step with Mr. Trump and his administration, rejecting suggestions that Congress must reassert its war powers in light of the recent hostilities with Iran. They contend that Mr. Trump showed restraint and was well within his authority to respond to an imminent threat.
Representative Kevin McCarthy of California, the Republican leader, spurned the resolution as toothless.
“This is the type of resolution that we use to invite the Soapbox Derby to the Capitol,” he said.
Other Republicans took up an argument that Mr. Trump’s advisers have made privately to lawmakers in recent days, that questioning the president’s authorization to confront Iran militarily is dangerous and unpatriotic. Representative Daniel Crenshaw of Texas, a former Navy SEAL officer, accused Democrats of “seeking to undermine” the American military and intelligence community by sowing “division and self-doubt.”
“While legitimate questions were raised, those questions have long been answered clearly and convincingly,” Mr. Crenshaw said on the House floor. “The president has a clear authority to respond to attacks against American citizens and U.S. forces.”
Mr. Trump took to Twitter before the vote to oppose the measure.
“Hope that all House Republicans will vote against Crazy Nancy Pelosi’s War Powers Resolution,” he wrote.
Later at the White House, the president tried out a new rationale for having targeted General Suleimani, claiming without offering evidence that the Iranians were “looking to blow up our embassy” in Baghdad.
Only one Republican, Representative Matt Gaetz of Florida, joined Democrats in voting to advance the measure on Thursday. Mr. Gaetz, while an outspoken ally of Mr. Trump, has also been among the small group of Republicans in Congress pressing to disentangle the United States from foreign wars and insist that the president seek authorization for military operations.
Congress enacted the War Powers Resolution in 1973 over President Richard M. Nixon’s veto, empowering Congress to pass legislation that directs a president to terminate military action unless lawmakers have explicitly voted to authorize them. But lawmakers have never succeeded in using it to curb a military operation, in part because it appeared to be severely weakened by a Supreme Court decision a decade later that struck down a similar legislative veto mechanism in an unrelated immigration law.
Since then, it has been broadly understood that Congress must use joint resolutions to try to terminate a war, essentially meaning that it takes the votes of two-thirds of lawmakers in both chambers — the amount needed to override a veto, which is politically far more difficult to achieve. Last year, for example, the Senate and the House both passed a joint resolution to force Mr. Trump to end support for Saudi Arabia’s intervention in Yemen’s civil war. But Mr. Trump vetoed it, and an override vote in the Senate failed 53 to 45.
The Senate could move as soon as next week to take up a similar resolution on Iran sponsored by Senator Tim Kaine, Democrat of Virginia. That measure faces an uphill climb in the Republican-controlled Senate, but the administration briefing delivered to senators Wednesday so enraged two Republicans in the chamber, Senators Mike Lee of Utah and Rand Paul of Kentucky, that they said they would support it. That measure would mandate that Mr. Trump wind down military action against Iran within 30 days unless Congress voted to authorize it.
The support of the two libertarian-leaning senators, who have long clamored for Congress to rein in presidential war powers, means that Democrats, who control 47 votes, are within striking distance of the majority needed to pass it.
Two other Republicans, Senators Susan Collins of Maine and Todd Young of Indiana, said they were considering voting for Mr. Kaine’s resolution. But his version is a joint resolution that Mr. Trump could veto.