WASHINGTON — Senate Republicans introduced a measure Tuesday night that would curtail future presidential emergency declarations in a last-ditch effort to save President Trump’s current border wall emergency from an embarrassing rejection by senators charging constitutional overreach.
Four Republican senators have publicly said they will support a House-passed resolution of disapproval when it comes up for final passage in the Senate on Thursday. That would be just enough to ensure passage of a measure overturning the national emergency that the president declared to secure border wall funding over Congress’s objection.
But that near certainty appeared to shift on Tuesday as Vice President Mike Pence pressed Senate Republicans at a closed-door meeting before their weekly policy lunch. A measure sponsored by Senator Mike Lee, Republican of Utah, and supported by more than a dozen Republican senators, would curtail the president’s powers under the National Emergencies Act of 1976, requiring a congressional vote of approval for any new emergency declaration after 30 days.
And one of the Republicans who said he favored the resolution of disapproval, Senator Thom Tillis of North Carolina, appeared to be wavering, according to multiple people at the policy lunch. Without him — and barring any other defections — the resolution would fail to reach the president’s desk.
“If you would have asked me before this lunch then I would have said, in the Senate, the president is going to lose,” said Senator John Kennedy, Republican of Louisiana, who opposes the resolution. “But I’m not so sure now. A lot of people are trying to think of a way to express their support for the president, but at the same time express their concern” about ceding too much power to the White House.
While Mr. Lee’s bill would not retroactively apply to Mr. Trump’s border emergency declaration, it would give Senate Republicans cover — and offer their only chance of defeating the House resolution by easing concerns that a future Democratic president could take advantage of the precedent set by Mr. Trump.
Mr. Lee, who declined to say how he would vote on the resolution, recast the issue as the Senate reasserting its constitutional prerogatives — in the future.
“Over the last 80 years, Congress has voluntarily relinquished a whole lot of legislative power, handed over to the executive branch,” said Mr. Lee, speaking to reporters about his bill. “We’ve deviated so far from the structure put in place by the Constitution.”
Passing the resolution to overturn the border emergency would represent a rare assertion of legislative prerogative by Senate Republicans, who have been loath to buck Mr. Trump over the last two years. The measure would almost certainly be vetoed, the first of Mr. Trump’s presidency, but it could also bolster several lawsuits contesting the president’s emergency declaration as a flagrant violation of the Constitution, which grants Congress the power to decide how to spend federal tax dollars.
Senate Democrats responded incredulously to the Republican maneuver.
“I think Leader McConnell all too often has abandoned what is good for the comity in the Senate and the institution of the Senate to go along with President Trump,” Senator Chuck Schumer, the Democratic leader, said in an interview on Tuesday.
He said Democrats would oppose any attempt to curtail future abuses of executive power without addressing Mr. Trump’s actions.
The resolution of disapproval has squeezed Mr. Tillis between conservatives in his home state angered by his stand and the swing voters he needs for his re-election in 2020.
Mr. Trump has added his own pressure. In conversations with staff members and lawmakers, the president has made an emotional case for opposing the resolution, telling them that a vote in favor would be seen by their constituents as “a vote against border security” and warning that such a move would be regarded as disloyalty, according to three Republicans with direct knowledge of his actions, who spoke on the condition of anonymity.
“This is not a free vote. The president is paying attention,” Senator Mitch McConnell, the Republican leader, told the conference during their weekly lunch at the Capitol, according to a person in attendance.
Mr. Lee then delivered an upbeat assessment of a meeting with Mr. Pence, telling his colleagues that the vice president agreed, in principle, to the idea of limiting the scope of an emergency declaration to 30 days without congressional approval — but insisted that it be measured in “legislative” days rather than calendar days, which could extend a president’s latitude for action, the person added.
Mr. Tillis, to the surprise of some in the room, embraced the idea — although he did not go so far as to say he would reverse his public support for the resolution. He is a co-sponsor of Mr. Lee’s bill.
It is unclear if Mr. Pence’s concession will be enough. A handful of other Republicans have privately signaled they may also buck the West Wing to ensure a clear statement from Congress that a president cannot use an emergency declaration to secure funds for a project that was explicitly rejected by the branch of government constitutionally granted control of federal spending.
“We’ve got a short window for something to come together,” Senator John Thune, Republican of South Dakota, the No. 3 Republican in the Senate, told reporters on Tuesday.
Other senators, he said, would likely “feel comfortable in the end voting against the resolution as long as they had something they could point to that actually is modernizing the underlying statute.”
Both Senators Susan Collins, Republican of Maine, and Lisa Murkowski, Republican of Alaska, have publicly declared their intent to disapprove of Mr. Trump’s declaration and gave no indication on Tuesday that they had changed their minds.
Senator Rand Paul, Republican of Kentucky, is also a “yes” vote, and told reporters on Tuesday that while it was unlikely that he would change his mind on supporting the resolution, he would support reforming the National Emergencies Act.
The compromise proposed by Mr. Lee also seemed to soothe other Republican senators who have criticized the president’s actions but have been unwilling to publicly support the motion of disapproval.
Senator Roy Blunt, Republican of Missouri, has not publicly said how he will vote on the resolution, but he thought the Lee bill would help keep defections to a minimum. Mr. Trump had been a sharp critic of presidents exceeding their authority when the president was Barack Obama.
“The president had problems, as a candidate, with the Obama overreach,” Mr. Blunt said. “He’s been on the record for some time on this topic, and I think this would give him a chance to get back to where he was three years ago.”