WASHINGTON (AP) — President Joe Biden on Tuesday urged Congress to "show some spine" and stand up to Donald Trump even as a Senate deal on border enforcement measures and Ukraine aid rapidly collapsed.

Just minutes after the Democratic president's remarks at the White House, Senate Republican Leader Mitch McConnell emerged from a GOP luncheon at the Capitol and acknowledged that the deal was dead.

"It looks to me and to most of our members that we have no real chance here to make a law," the Kentucky Republican told reporters.

The split-screen moments in Washington represented a swift turn of events that showed McConnell's slipping control of his GOP conference, Trump's growing influence, and Biden's ability only to look on as a cornerstone of his foreign policy — halting Russian President Vladimir Putin's advance into Europe — crumbled in Congress.

Biden had engaged for months on a carefully negotiated plan to pair policies intended to curb illegal crossings at the U.S.-Mexico border with $60 billion in wartime aid for Ukraine. The bill was intended to exhibit American strength around the world and also would have sent tens of billions of dollars more for Israel, other U.S. allies in Asia, the U.S. immigration system and humanitarian aid for civilians in Gaza and Ukraine.

But after Republicans backed away from the compromise, the president and Senate leaders are now stranded with no clear way to advance aid for Ukraine through Congress. They have run into a wall of opposition from conservatives — led by Trump — who reject the border proposal as insufficient and criticize the Ukraine funding as wasteful.

Biden laid blame for the bill's demise squarely on Trump — his likely Republican opponent in the November presidential election.

"For the last 24 hours he's done nothing, I'm told, but reach out to Republicans in the House and the Senate and threaten them and try to intimidate them to vote against this proposal," Biden said. "It looks like they're caving. Frankly, they owe it to the American people to show some spine and do what they know to be right."

Senate Majority Leader Chuck Schumer cast Tuesday as a "gloomy day here in the United States Senate" during an earlier floor speech in which he scolded Republicans for backing away from the deal. He offered to delay a key test vote on the package until Thursday, but still dared them to vote against border security — an issue they have long championed.

"After months of good faith negotiations, after months of giving Republicans many of the things they asked for, Leader McConnell and the Republican conference are ready to kill the national security supplemental package even with border provisions they so fervently demand," Schumer said.

The White House has worked for months with senators on the carefully negotiated compromise in hopes that it would unlock Republican votes for the Ukraine aid in the House — where scores of GOP lawmakers have come out against funding Kyiv's fight against Russia.

The Pentagon is sending no more arms shipments to Kyiv just as the war — entering its third year — reaches a critical juncture. Ukraine is struggling with ammunition and personnel shortages while Russia is on the offensive, mounting relentless attacks.

"Every week, every month that passes without new aid to Ukraine means fewer artillery shells, fewer air defense systems, fewer tools for Ukraine to defend itself against this Russian onslaught," Biden said. "Just what Putin wants."

The lack of a national security deal will loom large over Biden's Friday meeting with German Chancellor Olaf Scholz. Biden plans to underscore to Scholz that he remains committed to providing Ukraine the funding it needs to continue to repel the nearly two-year old Russian invasion.

McConnell said in an earlier floor speech that it was essential to assert American strength in Europe, the Middle East and Asia, yet also blamed Biden for not responding sooner to threats from rival powers.

"Either we confront challenges we face with clear strategy and firm resolve or we lose," McConnell said.

Facing resistance from House Republicans to funding Ukraine, McConnell last year had insisted on pairing the money with border policy changes. But the longtime Republican leader has not been able to convince his conference to warm to the compromises on border security after Trump, the likely Republican presidential nominee, excoriated it.

Within hours of the bill's release Sunday, House Speaker Mike Johnson said he would not support it, and even GOP senators who had been supportive of the border policies under discussion came out against the bill on Tuesday.

The border proposal represents one of the most conservative and comprehensive proposals in decades to emerge from a bipartisan negotiation in Congress. It would seek to tamp down the historic number of illegal border crossings by making the asylum process tougher and faster. Presidential administrations would also be given authority to deny migrants from claiming asylum at the border if the number of migrants claiming asylum becomes unmanageable for authorities.

"We have a very conservative bipartisan border bill that fixes the problem at the border," said Connecticut Sen. Chris Murphy, who negotiated the bill for Democrats. "And it's time for the country to see where people stand on that."

But Republicans have largely heeded the wishes of Trump to reject the bill because it would show that Biden could act to address problems at the border, which is seen as one of his largest vulnerabilities in his reelection campaign.

"The politics of this were a big factor," said Sen. John Cornyn, a Texas Republican. "When the speaker said basically the Senate bill is dead on arrival. And then President Trump weighs in and discourages Republicans from voting for it."

Cornyn said he would support a move to jettison the border measures from the package and try to advance the aid for U.S. allies on their own.

But that idea also faces resistance in the Republican-controlled House, where Johnson has also left any support for Ukraine aid in doubt.

When asked about wartime aid for Ukraine and Israel Tuesday, he told reporters, "We have to deal with these measures and these issues independently and separately."

The House was scheduled to vote on a $17.6 billion package of military aid for Israel, but hardline conservatives have signaled opposition because the funding would not be offset with budget cuts in other areas.

House Democratic leaders also said they would not support the bill for Israel. In a letter to Democrats, House Democratic Leader Hakeem Jeffries, along with Reps. Katherine Clark and Pete Aguilar, said the bill was not being offered "in good faith" and urged Democrats to hold out for a package that addresses Ukraine and allies in Asia.

"It is a nakedly obvious and cynical attempt by MAGA extremists to undermine the possibility of a comprehensive, bipartisan funding package that addresses America's national security challenges in the Middle East, Ukraine, the Indo-Pacific region and throughout the world," they said.