Senator Chuck Schumer, Democrat of New York and the majority leader, said on Thursday that he would set up a test vote next week on a measure pairing an immigration crackdown with tens of billions of dollars in military assistance to Ukraine and Israel, but the package is facing a rough road with Republican resistance in both chambers.
Mr. Schumer’s promise came as a small group of Republican and Democratic senators rushed to finalize a plan to clamp down on migration across the U.S. border with Mexico, which Republicans had demanded be paired with any further aid to Kyiv for its war against Russian aggression.
Senate leaders in both parties have called the emerging border agreement the best chance in decades to address the intractable issue of immigration, and President Biden has endorsed it. But right-wing Republicans, egged on by former President Donald J. Trump, have denounced it as too weak, prompting Speaker Mike Johnson to call it dead on arrival in the House and indicating that it may have no path through Congress.
And since negotiators have yet to release the text of their agreement, it is not yet clear whether Senate Republicans will embrace or reject it. Mr. Schumer said the finished product would be public “no later than Sunday,” to give senators enough time to examine it before an initial vote expected by Wednesday.
“We are getting very close,” Mr. Schumer said on the Senate floor, arguing that the forthcoming bill would be a vital tool for “enabling us to address multiple crises around the globe.”
“Addressing these challenges is not easy, but we cannot simply shirk from our responsibilities just because a task is difficult,” he added.
The deal would make it more difficult for migrants to be granted asylum in the United States, increase detention capacity, step up deportations of individuals seeking to enter the country without authorization, and shut down the U.S.-Mexico border to new entries if crossings exceed a certain level.
It would be part of a package with an infusion of funding to Ukraine and to Israel for its war in Gaza, as well as humanitarian assistance for Palestinians under bombardment, and resources to help counter Chinese influence and threats in the Indo-Pacific region.
In recent weeks, leading Republicans in the House, and many rank-and-file G.O.P. senators, have denounced the compromise, arguing that it is not stringent enough to make an appreciable difference in border crossings — and insisting the Biden administration cannot be trusted to implement the proposed measures fully.
Mr. Biden last week urged Congress to pass the deal, promising to use it to “shut down the border.” Mr. Johnson, a Louisiana Republican, tore into the president for those words in a speech this week on the House floor, arguing that he already had the power to close the border to most new arrivals.
“He falsely claimed that he needs Congress to pass a new law to allow him to close the southern border; he knows that’s not true,” Mr. Johnson said, adding: “This so-called deal does not include these transformational policy changes that are needed to actually stop the border catastrophe.”
The Senate’s planned vote on the border deal could coincide with the House G.O.P.’s plans to impeach Mr. Biden’s homeland security secretary, Alejandro N. Mayorkas, as soon as next week, on charges of refusing to enforce border laws and breaching the public trust. The Biden administration and several leading constitutional law experts, including conservatives, have argued that the case is a policy dispute that does not rise to the level of an impeachable high crime or misdemeanor.
Senate Republican leaders and those close to the negotiations have been trying to persuade skeptics not to listen to the critics until they see the text of the deal for themselves. But the longer it takes to finalize a deal, the more they are concerned about losing ground.
“If we don’t get this published, and build momentum, like I said earlier, the hill keeps getting steeper,” Senator Thom Tillis, Republican of North Carolina, told reporters on Thursday.
The resistance in the House and by Mr. Trump, who is the front-runner for the Republican presidential nomination, is proving to be a significant obstacle. Last week, Senator Mitch McConnell, Republican of Kentucky and the minority leader, warned that Mr. Trump’s hostility to the deal had put Republicans “in a quandary.”
On Thursday, when asked whether his colleagues would be able to overcome Mr. Trump’s opposition and embrace the deal, Senator John Thune of South Dakota, the No. 2 Republican, said: “I can’t answer that yet.”
Democrats said time was running out for the compromise, noting that Republicans, who demanded a border deal in the first place, were now threatening to stand in the legislation’s way.
“They’re making a decision as to whether they want to do what they said they wanted — to pass a bipartisan border bill — or whether they want to do the bidding of Donald Trump,” said Senator Christopher S. Murphy of Connecticut, the lead Democrat in the border talks. “Every day that goes by in which they don’t commit to funding the deal is a day that we’re closer to their decision being made in favor of Donald Trump.”