With time slipping to bolster Ukraine's defenses, Senate negotiators struggled Wednesday to finalize a bipartisan deal that would pair policy changes at the U.S. southern border with wartime aid for Kyiv as their carefully negotiated compromise ran into strong resistance from House Republicans and Donald Trump.

Senate negotiators have kept a close hold on the details of a bipartisan package on border enforcement and immigration policies that was supposed to unlock Republican support in Congress for aiding Ukraine. But conservatives view the tens of billions of dollars in proposed support with growing skepticism, unmoved by arguments about the larger stakes for global security. NATO Secretary-General Jens Stoltenberg was making the case for the aid on Capitol Hill Wednesday, including at the Heritage Foundation, a power center for Trump's allies in Washington.

President Joe Biden, who is pushing for a deal alongside Republican and Democratic leaders in the Senate, faces a daunting task in convincing Republicans to defy Trump's wishes and embrace the deal — especially in the midst of an election year.

Republican leaders, including House Speaker Mike Johnson, had looked to February as a potential deadline to approve another tranche of military aid for Ukraine. But the $110 billion national security package that congressional leaders say is essential to buttressing American allies around the globe, including Ukraine, Israel and Taiwan, has been swept up in the fight over border policies.

Meanwhile, Ukrainian troops are running short of weapons, including air defenses and artillery to defend against Russia's ongoing attack. The Pentagon reported last week it is out of money for Ukraine.

Senate Majority Leader Chuck Schumer, D-N.Y., warned in a morning floor speech that "the survival of Ukraine is on the line."

"The only way we'll rise to the occasion is if both sides are serious about finding a bipartisan compromise," he said, adding, "We have not concluded negotiations so we will keep going to get this done."

"Here in the Senate, both sides have an obligation to tune the partisan noise out and to continue working," the New York Democrat added.

But there's frustration among lawmakers who haven't been part of the talks.

“I don't know if it's dead, but it's I think it's ridiculous that no one's seen this language," Missouri Sen. Eric Schmitt told Spectrum News.

Even if the Senate is able to finish the deal and pass it, resistance is strong in the House, where Trump, the likely Republican presidential nominee, holds significant sway over lawmakers.

“As the leader of our party, there is zero chance I will support this horrible, open borders betrayal of America,” Trump said at a rally on Saturday. “It’s not going to happen, and I’ll fight it all the way.”

“I notice a lot of the senators, a lot of the senators are trying to say, respectfully, they’re blaming it on me,” Trump continued. “I said ‘that’s OK, please blame it on me.’ Please, because they were getting ready to pass a very bad bill. And I’ll tell you what, a bad bill, I’d rather have no bill than a bad bill.”

Trump has previously slammed the bill as “another Gift to the Radical Left Democrats,” writing in a post on his Truth Social platform last week: “They need it politically, but don't care about our Border.”

Trump’s comments drew condemnation from his main opponent in the Republican presidential primary, former U.N. Ambassador Nikki Haley, who said on NBC’s “Meet the Press” that “the last thing he needs to do is tell them to wait to pass a border deal until the election.”

“My message to Republicans is: Do not leave D.C. until you finish the job. We have waited for so long for Congress to do something about the border,” Haley said, later adding: “We can't wait one more day” for a border bill.

Trump's opposition has left Republican leaders increasingly questioning whether the border legislation should be jettisoned from the package in a last-ditch effort to get the Ukraine funding through Congress.

"It's time for us to move something, hopefully including a border agreement, but we need to get help to Israel and to Ukraine quickly," said Senate Republican Leader Mitch McConnell.

Other Republicans have decired efforts to kill the immigration bill, including Utah Sen. Mitt Romney, who called efforts to kill the bill "appalling," and North Carolina Sen. Thom Tillis, who called it "immoral" to not address the border.

“I didn’t come here to have the president as a boss or a candidate as a boss. I came here to pass good, solid policy,” Tillis said last week. “It is immoral for me to think you looked the other way because you think this is the linchpin for President Trump to win.”

Johnson discussed the idea of splitting up parts of the national security package in a Tuesday meeting with the speakers of the parliaments of Latvia, Estonia, and Lithuania, but did not commit to any course of action, a person familiar with the meeting told The Associated Press.

The speaker has long been skeptical of sending economic assistance to Kyiv, though he has also said he wants to halt Russian President Vladimir Putin's advance in Europe. But a large portion of Johnson's conference in the House is more firmly against the aid.

Stoltenberg, the longest-serving chief in NATO's history, pleaded Wednesday for lawmakers to act. In a speech Wednesday at the Trump-aligned Heritage Foundation, he warned that Putin's ambitions don't just end with Ukraine. He said the Russian president is intent on "reestablishing Russia's sphere of influence and shaping an alternative world order."

As Russian forces and drone attacks pummel the region, the Ukrainians will face increasingly difficulty defending their cities and populations from incoming assaults.

Yet Republicans also want to cut portions of the package that would not go directly to Ukraine's defenses. Of the $61 billion in the package for Ukraine, a portion, about $16 billion, would go toward economic, security and operational assistance.

The U.S. economic aid has been keeping the Ukrainian government functioning, paying for public works and employees and the services they provide, but Republicans prefer the U.S. focus its spending on military hardware to win the war.

"Here in the Senate, both sides have an obligation to tune the partisan noise out and to continue working."The economic assistance for Ukraine is expected to be trimmed back in the final supplemental package, according to a person familiar with the situation and granted anonymity to discuss it. The person said changes in the amount of humanitarian aid for Gaza, which was stripped from the package by House Republicans, are also being discussed.

Senate Republicans initially insisted on pairing border policy changes with Ukraine aid as part of a strategy to push the package through Congress. But so far, compromising on border policies has only made things more difficult.

Trump has seized on a key compromise in the bill that would expel migrants seeking asylum at the border once illegal crossings rise above 5,000 daily. Speaking to reporters after a meeting with the Teamsters union in Washington Wednesday, he called the bill "terrible," but denied his opposition had anything to do with presidential politics.

"If the bill's not going to be a great bill and really solve the problem, I wouldn't do it at all," Trump said.

Johnson, who has consulted with Trump on border policy in recent weeks, also told fellow Republicans in a closed-door meeting on Tuesday morning that the provision is a "non-starter" in the House. While he has said he has not passed final judgement on the bill, he is poised to reject any compromise.

Sen. Kyrsten Sinema, an Arizona independent who has been central to Senate talks, said the group was close to releasing text but was still working through the intricacies of writing immigration law. She urged lawmakers to keep an open mind to the legislation.

Sinema called it "factually false" for conservatives to claim that the proposal would allow 5,000 migrants to enter the country daily. The expulsion authority would be one part of a new system that includes raising the initial standard to receive asylum protection and quickly processing asylum claims.

Migrants who apply for asylum at ports of entry would be put in a "removal authority program," in which their asylum case is decided within six months, Sinema said. And migrants who seek asylum in between ports of entry would be put into detention and removed within 10 to 15 days if they fail initial interviews, known as credible fear screenings.

"It ensures that the government both has the power and must close down the border during times when our system is overwhelmed, and it creates new structures to ensure that folks who do not qualify for asylum cannot enter the country and stay here," she said. "It is a very robust package."

Sinema said Johnson's team is familiar with the details of the bill.

Still, Johnson on Wednesday used his inaugural floor speech since becoming speaker to lay blame on Biden's handling of the border and rally Republicans to insist on hardline border measures, even though those policies have virtually no chance of passing the Senate.

"Rather than accept any accountability or responsibility for what they've clearly done President Biden wants to somehow shift the blame to Congress for his administration's catastrophe by design," Johnson said.

But House Democrats are accusing their GOP counterparts of "sabotaging" the accord, despite similarly not knowing what's in it. They also took aim at the GOP-led effort to impeach Homeland Security Secretary Mayorkas, which Republicans advanced along party lines in early Wednesday.

"One party ... they just want to sabotage the process, throw out the secretary in charge of the process, not solve the process," California Rep. Eric Swalwell told Spectrum News.