WASHINGTON — President Trump has stepped back from declaring a national emergency to pay for a border wall, under pressure from congressional Republicans, his own lawyers and advisers, who say using it as a way out of the government shutdown does not justify the precedent it would set and the legal questions it could raise.
“If today the national emergency is border security, tomorrow the national emergency might be climate change,” Senator Marco Rubio of Florida, one of the idea’s critics, said this week. Another Republican, Senator Mitt Romney of Utah, told an interviewer that declaring a national emergency should be reserved for “the most extreme circumstances.”
Mr. Trump, who according to aides has grown increasingly frustrated over the refusal of Democrats to bend and sees the shutdown as a road with no off-ramp in sight, hinted on Friday that the warnings were having an effect.
“What we’re not looking to do right now is national emergency,” he told reporters gathered in the Cabinet Room as the shutdown approached its fourth week. Minutes later he contradicted himself, saying that he would declare a state of emergency if he had to.
As Speaker Nancy Pelosi and Senator Chuck Schumer, the minority leader, have proved immune to Mr. Trump’s threats, the idea of using the president’s constitutional powers to declare an emergency has received close scrutiny in the White House because it would enable Mr. Trump to obtain the $5.7 billion he has sought for construction of a wall without the approval of Congress.
Instead, Mr. Trump would use his authority to transfer funds to the wall that were appropriated by Congress for other purposes. Toward that end, the Army Corps of Engineers has been directed to study whether it can divert about $13.9 million in emergency aide set aside for Puerto Rico, Florida, Texas and California. And with the money secured, the president could drop his opposition to the appropriations bills whose passage would end the shutdown.
That would allow Mr. Trump to say he had never backed down from his fight with congressional Democrats or abandoned his pledge to build the wall even if the construction became tied up in legal challenges.
Former White House aides, who noted that Mr. Trump did not focus on the wall during the first two years of his presidency, said the optics of fighting for the wall were more important to the president than erecting it.
But opposition has come from many Republican quarters. Some conservatives see it as an unacceptable extension of executive power. Kellyanne Conway, a White House aide, has said it would essentially give Congress a pass. Representative Mike Simpson, Republican of Idaho and a member of the House Appropriations Committee, said it was not clear to him that an emergency declaration would even lead to the prompt reopening of the government.
He called it “a bad escape hatch” that was “going to piss off a lot of members.”
Mr. Trump’s reluctance is also frustrating allies ginning him up to take action. “If it’s a crisis, treat it like a crisis,” Stephen K. Bannon, the former chief White House strategist, said in an interview. “His best option now is to declare a national security emergency and get on with it.”
On Thursday, Mr. Trump traveled to the border in Texas to dramatize his support for a wall but used a photo-op along the banks of the Rio Grande on Thursday only to repeat his familiar arguments for building it. He sidestepped the issue when Sean Hannity, the Fox News host, asked him in an interview that night to detail what a national emergency would look like.
“There’s some compromise needed,” Mr. Trump said.
But Mr. Trump, who allies said was eager to spend time at his Mar-a-Lago club in Florida and resented the advice of aides to deliver an Oval Office address and travel to Texas on Thursday, is left with few good options.
As he searches for a way to end the political stalemate with Democratic lawmakers, Mr. Trump is finding himself boxed in, in a familiar position when it comes to immigration issues. Former aides say that is because he conflates legal and policy issues with public relations campaigns and does not anticipate an endgame.
In March, Mr. Trump was facing pressure to meet a deadline on a decision about what to do with immigrants who were part of the Deferred Action for Childhood Arrivals program, which allowed young adults brought to the United States illegally as children to avoid deportation and become eligible for a work permit.
Racked by anxiety as he quizzed aides for advice, Mr. Trump turned to an adviser and asked, “How do I get out of this?”
In the end, Mr. Trump was saved, at least temporarily, by a federal appeals court ruling last year that he could not immediately end the program. Mr. Trump moved on.
In the opening weeks of his presidency, Mr. Trump issued an executive order banning citizens from seven majority-Muslim countries from entering the United States. That ban was almost immediately halted in court. A second, rewritten version, however, was upheld by the Supreme Court and was seen as at least a partial victory for the administration.
But Mr. Trump vented, privately and publicly, that the version that passed legal muster was “watered down” and “P.C.,” and made him look “weak.”
How Mr. Trump found himself in his most recent predicament can be traced back to September, when White House aides and conservative lawmakers urged the president to engage in a fight for wall funding. But he was told to postpone the fight until after the election, to avoid forcing vulnerable Republicans in swing districts to take a politically perilous stance on the wall.
When he looked like he might compromise and support a bill that provided far less money for the wall than he asked for, conservatives like Ann Coulter excoriated him, describing him as “gutless,” and he backed down. Soon he was telling Mr. Schumer and Ms. Pelosi during a televised Oval Office meeting last month that he would proudly “own the shutdown,” thrilling conservatives.
Buoyed by the praise, and encouraged by the acting White House chief of staff, Mick Mulvaney, Mr. Trump decided to keep digging in.
But that encouragement for what played well in a viral television moment never led to a coherent strategy for a prolonged stalemate, according to a half-dozen people in the White House or working with the administration on a way to end the shutdown.
Mr. Trump’s allies insist that he is winning the political battle.
“Democrats are boxed in,” said Greg Mueller, a conservative strategist. “Every time the president and G.O.P. go to the Democrats with a fix, they say no, which positions them as obstructionists ignoring the problem, and opening themselves up for major troubles in 2020.”
Senator Lindsey Graham, Republican of South Carolina, who had tried and failed to find an alternative to reopen the government earlier in the week, emerged from a meeting with Mr. Trump on Friday declaring that it was clear Democrats “don’t want to make a deal and will never support border wall/barriers.”
And he encouraged the exact action many of his colleagues were warning against. “Mr. President, declare a national emergency now,” he said. “Build a wall now.”
Mr. Trump’s aides said they expected the stalemate over the wall funding to be resolved by the time he delivers the State of the Union address on Jan. 29. But the White House also has drafts based on the shutdown being over — or well into its sixth week.