By Jordain Carney and Rebecca Kheel, The Hill–

President Trump is digging in on potentially declaring a national emergency to construct the U.S.-Mexico border wall, a move that would set up a clash with Republicans on Capitol Hill.

Declaring migration at the southern border a national emergency may be Trump’s best option for a quick off-ramp to end the partial shutdown, which is now in its 20th day with little to no progress toward a negotiated agreement.

The president and White House officials aren’t ruling out taking the controversial step as they search for an exit strategy. Trump raised the possibility several times on Wednesday, at one point saying he “may” make an emergency declaration if he can’t get a deal with congressional Democrats who participated in a third White House meeting.

“I may do that at some point,” Trump told reporters after a closed-door meeting with Senate Republicans.

He added that he might do so if Senate Minority Leader Charles Schumer (D-N.Y.) and Speaker Nancy Pelosi (D-Calif.) “don’t agree to the fact that our country has really got problems with crime, with drugs, with a lot of other things that come through our southern border.”

An agreement between Trump and Democrats appeared to move further away after Wednesday’s brief White House meeting, which the president blasted as a “waste of time.”

Republican senators are wary of crossing Trump on major issues like the border, where the party’s base is pressuring Trump not to cave, and many have stopped short of flatly opposing using an emergency declaration or issuing ultimatums to the president.

But leapfrogging Congress by declaring a national emergency would fly directly in the face of public warnings from Republican lawmakers, including some of the president’s traditional allies in Congress. Several are making clear they would prefer to resolve the stalemate through negotiations, characterizing a national emergency declaration as the “last thing you do” and urging the president to “tread lightly.”

Sen. John Cornyn (R-Texas) warned that it could guarantee the fight over the border wall drags on for years and tie the administration up in a lengthy legal challenge that would effectively halt progress on Trump’s goal of building the wall.

“I think it adds new layers of complexity because we know the first thing that will happen is somebody will file a lawsuit, and it won’t be resolved for weeks, maybe months, maybe even years,” Cornyn said.

When asked if using an emergency declaration would at least let Trump and Congress end the shutdown, Cornyn grimaced and said, “I don’t think that resolves much of anything.”

Mitch McConnell et al. posing for the camera: Emergency declaration option for wall tests GOP© Greg Nash Emergency declaration option for wall tests GOPSen. Roy Blunt (R-Mo.), a member of GOP leadership, said “there are many ways out of the shutdown.” But when pressed if a declaration was one of those paths, he said it “would not have been my initial thought as one of the ways out of this.”

Sen. Thom Tillis (R-N.C.) brushed off questions about whether he would support an emergency declaration, saying he was instead interested in putting “pressure on Congress to come up with a long-term solution.”

“You can’t be in a national emergency forever. For us to totally secure the border, that’s a multiyear proposition,” he said when asked if declaring an emergency would take pressure off Congress for now.

The contention over using the declaration option is the latest sign of division between Senate Republicans and Trump over the party’s shutdown strategy. The chamber passed a stopgap measure late last month to prevent a partial shutdown, but Trump, under fire from conservative pundits, opposed the measure and has since doubled down on his demand for more than $5 billion in wall funding.

Trump and Majority Leader Mitch McConnell (R-Ky.) tried to emphasize party unity after a closed-door Senate lunch with Trump and Vice President Pence. Trump said Republicans were “totally unified” on the border strategy, while the tight-lipped GOP leader said senators were “behind” the president.

“We’re sticking with the president on this,” McConnell told reporters when he returned to the Capitol from the White House meeting later that day.

But a growing number of Republican senators are getting antsy as the partial government closure is heading toward a record as the longest shutdown. Two moderate senators – GOP Sens. Susan Collins (Maine) and Lisa Murkowski (Alaska) – confronted Trump during the closed-door meeting about the effect of the partial shutdown, which has left roughly 800,00 federal workers furloughed or working without pay.

Republican senators say the idea of using a national emergency to construct the wall along the southern border was mentioned during the closed-door meeting with Trump at the Capitol, which lasted more than an hour, but indicated it wasn’t a significant point of discussion.

“I think there’s some concern. I believe he’s heard those, about how it could be used by future presidents for other reasons,” Sen. Marco Rubio (R-Fla.) said after the meeting.

Collins, speaking with reporters, dismissed the idea of Trump declaring a national emergency in order to construct the border wall as “dubious” and questioned whether the administration could unilaterally move money out of the Pentagon’s budget.

“Although the president does have national emergency declaration powers … this would be a dubious constitutional authority and would clearly be challenged in the courts. I think a far better approach is for the president to work with members of Congress to come up with a compromise,” she said. “I just don’t think you can repurpose more than $5 billion from the defense budget for purposes unrelated to what the money was appropriated for.”

A Pentagon spokesman declined to comment Wednesday on the possibility of Trump declaring a national emergency to use military funding for the wall, saying it is a hypothetical question because “we currently have no such order.”

When Trump discussed using military funding in December, the Pentagon said in a statement to reporters that it had no plans to build the wall. But the statement added that “Congress has provided options under Title 10 U.S. Code that could permit the Department of Defense to fund border barrier projects, such as in support of counter drug operations or national emergencies.”

The relevant section of Title 10 says that in the event of a national emergency, the Defense secretary can use military construction funding that has yet to be committed to a specific contract for other projects that support the Armed Forces.

Sen. James Inhofe (R-Okla.), chairman of the Senate Armed Services Committee, said using an emergency declaration wasn’t his preferred route, but that he could support it and thought there was a way to avoid dipping into Pentagon funding.

“We need to move it, and if you don’t see another path forward and that’s the only path, we’re going to have to do it,” Inhofe said. When asked if he saw another path, Inhofe replied: “I don’t see one. Do you?”

Sen. John Kennedy (R-La.) stressed that he wasn’t recommending Trump declare a national emergency, while simultaneously downplaying the controversy.

“I know there are some of my colleagues – and I’m not recommending the fourth option, please don’t misunderstand me – but some of my colleagues think it will be the end of western civilization if he does that,” he said. “I don’t.”