President Biden fought on Friday to save a bipartisan immigration deal from collapse in Congress, vowing to shut down the border if the plan became law even as the Republican speaker pronounced it dead on arrival in the House.
In a written statement that came as Senate negotiators scrambled to finalize a deal that President Donald J. Trump is pressuring Republicans to oppose, Mr. Biden used his most stringent language yet about the border, declaring it “broken” and in “crisis” and promising to halt migration immediately if Congress sends him the proposal.
“What’s been negotiated would — if passed into law — be the toughest and fairest set of reforms to secure the border we’ve ever had in our country,” he said. “It would give me, as president, a new emergency authority to shut down the border when it becomes overwhelmed. And if given that authority, I would use it the day I sign the bill into law.”
The pending compromise would not give him much choice. Under the emerging deal, the administration would be required to shut down the border to migrants attempting to enter without prior authorization if encounters rise above 5,000 on any given day — a threshold that has been surpassed routinely in recent months.
Mr. Biden’s fresh efforts to salvage the deal came hours after Speaker Mike Johnson sought to choke off the last remaining glimmers of hope that it might survive, repeating that the agreement would almost certainly be a nonstarter in the Republican-led House.
“If rumors about the contents of the draft proposal are true, it would have been dead on arrival in the House anyway,” Mr. Johnson wrote in a letter to House G.O.P. lawmakers.
It was the latest grim prediction for the proposed border agreement after the top Senate Republican conceded this week that Mr. Trump’s opposition had made the plan politically difficult for the party to embrace, all but killing its chances.
Mr. Biden’s Friday evening statement amounted to a counterpunch against Mr. Trump’s efforts to kill the deal, pitting the current and former commanders in chief against each other in a high-stakes fight over what is shaping up to be a central issue in the presidential campaign.
As the immigration plan teeters on Capitol Hill, the fate of additional aid for Ukraine also hangs in the balance, with hard-right House Republicans also dug in against it and threatening to depose Mr. Johnson if he seeks to push it through over their objections.
In his letter, Mr. Johnson said the House would move ahead next week with its drive to impeach Alejandro N. Mayorkas, the homeland security secretary, and doubled down on his demands that Congress embrace either an immigration crackdown bill the House passed last year or an equally severe measure.
“Since the day I became speaker, I have assured our Senate colleagues the House would not accept any counterproposal if it would not actually solve the problems that have been created by this administration’s subversive policies,” he wrote.
Mr. Biden’s words were unlikely to move the growing number of skeptical Republicans who have argued that the president already has the tools and the executive power he needs to dramatically restrict who enters the country — and refuses to use them.
“Many of our constituents have asked an important question: ‘What is the point of negotiating new laws with an administration that will not enforce the laws already on the books?’” Mr. Johnson wrote in his letter. “If President Biden wants us to believe he is serious about protecting our national sovereignty, he needs to demonstrate his good faith by taking immediate actions to secure it.”
The letter reflected a stance Mr. Johnson and other hard-right Republicans in the House have maintained for months, repeatedly dismissing the border enforcement measures under discussion in the Senate as insufficient. It came as Republican proponents of the deal in the Senate toiled to build needed G.O.P. support to push it forward. That task has grown much more difficult as Mr. Trump, who has savaged the plan, has gained ground in his quest for the party’s presidential nomination.
Senator Mitch McConnell of Kentucky, the minority leader, told fellow Republicans behind closed doors this week that Mr. Trump’s hostility to the plan and his growing dominance in the primary had put them “in a quandary.”
Mr. McConnell, a chief Republican proponent of sending more aid to Ukraine, has been a vocal supporter of the border deal that members of his party have insisted upon as the price of their backing for continued assistance for Kyiv.
The bipartisan team of senators that has been working for months to strike a compromise to crack down on rampant migration and drug trafficking across the southern border with Mexico has come to an agreement in recent days on a set of policy changes. They include measures to make it more difficult to secure asylum, increase detention facilities, and force the administration to turn away migrants without visas if more than 5,000 people attempt to cross into the country unlawfully on any given day.
The group has not yet agreed on how much money to devote to the effort.
Many Republicans are upset that the deal does not include a specific restriction on parole, the administration’s authority to let migrants not otherwise legally authorized to enter the country live and work in the United States on a temporary basis. In his letter on Friday, Mr. Johnson repeated his demand for more restrictive changes, such as placing strict limits on parole and reviving the Trump-era “Remain in Mexico” policy that forced migrants who could not be kept in detention facilities to wait outside the United States until their court dates.
And some Republican opponents of the border compromise have questioned the wisdom of bothering to consider it in the Senate if their counterparts in the House are determined to block or kill it.
“If you’re going to take a tough vote, you want it to actually accomplish something,” said Senator J.D. Vance, Republican of Ohio. “If it’s not going to pass the House, then it doesn’t make a ton of sense to force a vote on your membership that isn’t going to accomplish anything from a policy perspective, and it’s going to cause a lot of problems politically.”