WASHINGTON — The House voted on Tuesday to overturn President Trump’s declaration of a national emergency on the Mexican border, with just 13 Republicans joining Democrats to try to block his effort to divert funding to a border wall without congressional approval.
House Republican leaders kept defections low after feverishly working to assuage concerns among rank-and-file members about protecting congressional powers and about the precedent that Mr. Trump could be setting for Democratic presidents to use for their own purposes.
“Is your oath of office to Donald Trump or is it to the Constitution of the United States?” Speaker Nancy Pelosi asked her Republican colleagues in a speech on the floor ahead of the vote. “You cannot let him undermine your pledge to the Constitution.”
The resolution of disapproval, which passed 245 to 182, must now be taken up by the Senate, where three Republicans have already declared their support, only one short of the number needed for Congress to ratify a stinging rebuke of Mr. Trump’s efforts.
It remains highly unlikely that opponents will muster the votes to overturn a promised veto of the resolution. But final passage of a measure to assert Congress’s constitutional authority over spending is sure to bolster numerous lawsuits that maintain that Mr. Trump’s declaration is an unconstitutional end run around Congress’s lawful power of the purse.
Many of the 13 Republicans who defected in the House were adamant in their arguments. Representative Jim Sensenbrenner of Wisconsin, a veteran lawmaker who once helped manage Republican efforts to remove Bill Clinton from the White House, made it clear he supported the border wall.
But, he said, “insufficient action — however frustrating it may be — is still the prerogative of the legislative branch. It is imperative that no administration, Republican or Democratic, circumvent the will of Congress.”
In the Senate, where lawmakers are required to vote on the resolution in the coming weeks, those concerns persisted. Even Senator Mitch McConnell of Kentucky, the majority leader and an open supporter of the declaration, declined to offer his opinion on the legal merits.
“We’re in the process of weighing that,” Mr. McConnell said when asked at a news conference on Tuesday. “I haven’t reached a total conclusion.”
“You can’t blame the president for trying to use whatever tool he thinks he has to address it,” he added.
But ahead of the Senate vote, lawmakers have not said what their next steps would be if the resolution to stop the emergency declaration fails.
Three Republican senators — Susan Collins of Maine, Thom Tillis of North Carolina and Lisa Murkowski of Alaska — have said that they will support the resolution, and several others have expressed extreme unease. Vice President Mike Pence and a Justice Department lawyer joined Republican senators on Tuesday for a lunch on Capitol Hill to outline what they maintained was the president’s statutory authority for the declaration and need for additional money.
Mr. Pence faced some frustration from senators about Mr. Trump’s decision to make the declaration and the legal grounds for doing so, particularly from Senator Rand Paul, Republican of Kentucky, according to three people familiar with the exchange who asked for anonymity to describe a private meeting.
When Mr. Paul argued that Mr. Pence, a former representative, would have opposed Mr. Trump’s use of an emergency declaration and compared it to President Barack Obama’s use of an executive order to establish protections for young undocumented immigrants under the Deferred Action for Childhood Arrivals program, Mr. Pence objected, according to one person. He argued that there was a difference between the two uses of executive power, according to two people.
A spokesman for Mr. Paul said that the senator had raised concerns, along with other senators, about the declaration in an exchange, but did not raise the comparison to DACA.
Mr. McConnell acknowledged that there had been “a fulsome discussion” during the meeting, and Senator Lindsey Graham, Republican of South Carolina and a close ally of the president, said he hoped that as a result of the discussion, “we will prevail.”
But some senators emerged from the lunch still reluctant to say how they would vote.
“Any action by the administration must comply with federal law, so I am reviewing and assessing the specific legal authorities and justifications put forth by the administration,” said Senator Ted Cruz, Republican of Texas. “I am very worried about the slippery slope that could occur.”
Some Republican lawmakers and aides said they were unconcerned because they were confident that they could prevent the two-thirds majority needed in both chambers to override a presidential veto, possibly the first delivered by Mr. Trump.
“There will be nowhere near the votes to override a veto,” Representative Steve Scalise of Louisiana, the Republican whip, said Tuesday morning at a news conference. “Ultimately, we’re going to stand with the president in making sure we can secure this border.”
The resolution of disapproval, under the National Emergencies Act of 1976, serves as the easiest mechanism for Congress to end Mr. Trump’s declaration. House Democrats are still weighing the possibility of joining one of the lawsuits that have been filed to challenge the merits of the declaration.
Democrats, who overwhelmingly endorsed the resolution of disapproval, framed the vote as an ultimatum on whether lawmakers would buck party loyalty in order to protect Congress’s constitutionally granted powers. Ms. Pelosi, in a floor speech on Tuesday, listed a number of instances in which House Republicans had objected to Mr. Obama’s use of executive power, vowing that “we are not going to give any president, Democratic or Republican, a blank check to shred the Constitution of the United States.”
Representative Joaquin Castro called the vote on the one-page resolution “the most important vote, probably in a generation, on the separation of powers.”
Mr. Castro, Democrat of Texas and the author of the resolution, warned Republicans that if the president’s declaration went unchallenged, the issue would resurface.
“If Congress lets this stand, if the courts let it stand, how am I to tell a future president that gun deaths that number in the tens of thousands every year in this country, or opioid deaths that number in the thousands in this country, are not an emergency?” Mr. Castro said in a brief interview. “Or climate change is not a national emergency?”
“If this becomes a short circuit to get other things done,” he added, “then how is a president not expected to use that tool in the future?”
The debate over the merits of Mr. Trump’s national emergency declaration has led some lawmakers to suggest that Congress should re-evaluate how much power it has shifted to the executive branch and the scope of the National Emergencies Act.
“The larger issue is Congress has delegated its authority to the White House in hundreds of instances,” said Senator John Cornyn, Republican of Texas. “I think we need to have a bigger conversation about the separation of powers and whether we want to continue to delegate all this authority to the next president.”
Overruling concerns from other Republicans, Mr. Trump this month outlined his intent to use $3.6 billion from military construction projects to build his promised wall along the southwestern border. In the lunch with Mr. Pence and the Justice Department lawyer, Republican senators secured a promise that they would be notified about details of which military construction projects would be affected before they voted on the resolution, according to two people familiar with the discussion.
Mr. Pence also assured senators that any money diverted from projects would most likely be replaced in the next year’s funding allocation, according to one person familiar with the discussion. While Senator Richard C. Shelby of Alabama, the chairman of the Senate Appropriations Committee, later told reporters that he was confident that effort would be successful, Democratic appropriators would most likely object.
House Democrats also pressed the Defense Department on Tuesday to release those details to Congress.
“We fear that reprogramming funding intended for military construction projects and counterdrug activities will come at the expense of troop readiness and departmentwide efforts to address the military’s aging infrastructure,” wrote Representatives John Garamendi, Democrat of California, and Doug Lamborn, Republican of Colorado, both members of the House Armed Services Committee.
Members of the House Appropriations Committee will hold a hearing on Wednesday to examine the effect of the declaration on military construction and readiness, and members of the House Judiciary Committee will hold a hearing on Thursday in part to examine Mr. Trump’s use of powers under the National Emergencies Act.
“The Congress of the United States needs to have a spine, and not lay at the feet of the president,” said Representative Steny H. Hoyer of Maryland, the majority leader. “That’s not what the people elected us to do.”