WASHINGTON — Top U.S. Senate negotiators said Thursday that final details on an immigration policy deal remain under debate in the U.S. Senate, despite outside pressure from GOP presidential front-runner Donald Trump to sink any agreement as he makes immigration his central campaign message.

The No. 2 Senate Republican and GOP whip, Sen. John Thune, said that negotiations on an immigration deal tied to the passage of a multi-billion-dollar global securities supplemental package are at “a critical moment, and we’ve got to drive hard to get this done.”

“If we can’t get there, then we’ll go to Plan B,” the South Dakota Republican said.

He did not go into details on what a “Plan B” would look like or if a deal on immigration would be removed from the supplemental, which would provide critical aid to Ukraine that some Republican and Democratic senators are advocating as the country runs low on ammunition in its war with Russia.

Funding seen as a last hurdle to final U.S. Senate immigration deal

Like in his first presidential campaign, Trump has made immigration a main theme, often referring to migrants claiming asylum at the Southern border as an “invasion.” On his social media site, Truth Social, he has urged congressional Republicans to not accept a deal.

During a closed-door meeting on Wednesday night, Senate Minority Leader Mitch McConnell of Kentucky acknowledged the difficulty of passing an immigration bill and the potential it would undermine Trump, the top Republican negotiator of the deal, Oklahoma Sen. James Lankford, told reporters at the Capitol.

But Lankford disputed that McConnell’s comments, which were first reported by Punchbowl News, meant a deal on immigration would be killed so that Trump can attack President Joe Biden on the issue.

“McConnell was laying out the political realities of where things are, and it was the elephant-in-the-room conversation,” Lankford said. “We’re in a political election season.”

But Republican Sen. Mitt Romney of Utah, a longtime Trump critic, told CNN that “the fact that (Trump) would communicate to Republican senators and Congress people that he doesn’t want us to solve the border problem, but basically wants to blame Biden for it — this is really appalling.”

Lankford said that he has not talked to Trump in months and that he, along with the bipartisan group of senators working on the border deal — Sens. Chris Murphy, Democrat of Connecticut, and Kyrsten Sinema, independent of Arizona — are still moving forward.

“It’s now the end of January, in the middle of the presidential primary season, so I think that’s the shift that has occurred that he’s just acknowledging,” Lankford said of McConnell. Trump on Tuesday sailed to victory in the New Hampshire presidential primary, following his victory in the Jan. 15 Iowa caucuses, with former United Nations Ambassador Nikki Haley his sole major remaining opponent.

It’s also unclear whether any eventual Senate deal will survive in the House, as GOP Speaker Mike Johnson of Louisiana is demanding hard-line House immigration legislation be adopted and is moving forward with impeachment proceedings for U.S. Department of Homeland Security Secretary Alejandro Mayorkas over his immigration policies.

Johnson has also thrown his support behind Republican Texas Gov. Greg Abbott, who is defying U.S. Supreme Court orders and the White House in keeping and installing razor wire along the Texas-Mexico border.

Parole targeted 

While no framework or bill text of a Senate deal has been released, some of the proposals put forth would curb the Biden administration’s use of parole authority, which the administration has heavily relied on to grant temporary protections to migrants by allowing them to live and work in the United States without visas.

The Biden administration has invoked its parole authority more often than previous administrations to manage the large number of migrants at the Southern border, according to data compiled by Syracuse University’s Transactional Records Access Clearinghouse, or TRAC, which compiles immigration data.

The deal is also likely to make changes to asylum law that would raise the bar for migrants claiming asylum.

Biden says he’s ‘ready to act’ on ‘significant’ changes at the border, including asylum

For four months, Lankford, Sinema, and Murphy have worked to strike a deal with the White House to free up more than $100 billion in supplemental global security aid to Ukraine, Israel, Taiwan, and for U.S. border security.

Senate Republicans have hinged their support for the global supplemental package on immigration policy changes.

If passed, it would be the most substantial change to immigration law in 30 years.

Whether a deal passes is up to Republicans, Murphy said.

“We have negotiated a border policy package, we did what Republicans asked us to do, and now they seem to be having a hard time actually closing the deal,” he said.

Murphy said that the negotiators have an outline that appropriators are considering. He added that he’s not sure if aid to Ukraine would be unlinked to changes in immigration policy.

“I think what is very scary to some Republicans is that the deal we have reached will actually fix a big part of the problem, and I know for Donald Trump and some Republicans, it’s not in their best interest for there to be policy changes that actually fix the broken asylum system, or give the president new tools to better manage the border,” Murphy said.

Sen. Steve Daines, the chair of the National Republican Senatorial Committee, the GOP campaign arm, said that he has not spoken to Trump about the immigration deal.

“It seems to me quite ironic that folks are blaming Trump for the border deal when this is Biden who created the problem and can solve the problem unilaterally through executive action,” the Montana Republican said.

South Carolina’s Lindsey Graham, a staunch Trump supporter, said that he’s talked to the former president and has “told him what we’re trying to accomplish,” but declined to answer questions if the deal could be passed without Trump’s approval.

Some Republicans reluctant to wait

Despite the push from Trump to quash the talks, some Senate Republicans said that they have an obligation to address the Southern border.

GOP Texas Sen. John Cornyn, who endorsed Trump earlier this week, said that “Texas can’t afford to wait 11 months,” referring to a potential second Trump presidency in 2025.

With GOP pushing hard on immigration, parole emerges as a make-or-break issue in Congress

“Some people have said, well, the (immigration) issue is going to go away, and so that’ll be denying President Trump the issue. I think that’s a fantasy,” Cornyn said. “You’re not going to turn off what’s happening at the border like a water faucet, so this is going to continue to be a problem and it’s obviously a very, potent, political issue.”

He said that while Trump is “an important voice,” the Senate “has a job to do, and we intend to do it.”

Lankford echoed the same sentiments, and expressed doubt that Republicans would be able to get substantial immigration policy done under a second term with Trump because “we tried to do some immigration work while President Trump was president (and) Democrats would not join us in that conversation, and I’m not sure that they would in the next administration in that time period as well.”

Lankford noted that the deal they are working on now, if passed, will set immigration policy for decades.

“It’s really setting what’s going to be the policy direction for a long time,” he said. “So I encourage people to have a longer look on this, to say, ‘What can we do to be able to make sure that we have a consistent policy that works better than what we have now?’”