Ukrainian President Volodymyr Zelenskyy met with President Joe Biden and congressional leaders on Tuesday, hoping to secure more U.S. assistance to fend off Russia’s invasion. But his visit faced hurdles as lawmakers clashed over immigration and border issues that threatened to delay the aid package.

Zelenskyy arrived in Washington for a high-stakes visit that the White House said came at a “critical time” for Ukraine, which has been fighting a war with Russia-backed separatists since 2014. He first met with senators from both parties at the U.S. Capitol, where he received expressions of support and solidarity.

Senate Majority Leader Chuck Schumer said it was a “productive meeting” and praised Zelenskyy for outlining the help he needs and how it will benefit the U.S. and its allies. He said Zelenskyy stressed the urgency of the situation and the danger of letting Russia prevail.

“He made it clear, and we all made it clear, that if we lose, [Russian President Vladimir] Putin wins and this will be very, very dangerous for the United States,” Schumer said.

Zelenskyy also met with House Speaker Mike Johnson, who was less enthusiastic about the prospects of passing the aid package. Johnson said he reiterated his support for Ukraine, but criticized the Biden administration for lacking “clarity and detail” on the strategy and oversight of the funds.

“What the Biden administration seems to be asking for is billions of additional dollars with no appropriate oversight, no clear strategy to win, and none of the answers that I think the American people are owed,” Johnson said. “I’ve also made very clear from day one that our first condition on any national security supplemental spending package is about our own national security. The border is an absolute catastrophe.”

Johnson said the House was not the problem, but rather the White House and the Senate, where Republicans have demanded changes to immigration and asylum policies in exchange for approving the roughly $110 billion aid package, which also includes funds for Israel and Taiwan.

Some GOP lawmakers have also questioned the wisdom of continuing to fund Ukraine, arguing that the money could be better spent on domestic issues.

The impasse has put the aid package in limbo, with time running out before the holiday recess. Secretary of State Antony Blinken warned on Sunday that the U.S. was “running out of resources already in the bank to continue to assist” Ukraine.

Senate Minority Leader Mitch McConnell, a longtime supporter of Ukraine, said on Monday that border provisions were a priority for him and his colleagues, but did not rule out a compromise.

Zelenskyy did not comment to the media as he met with various leaders at the Capitol. He was scheduled to meet with Biden at the White House later on Tuesday and hold a joint press conference.

White House National Security Council spokesman John Kirby said the meeting was an opportunity for Biden to reaffirm the U.S. commitment to Ukraine’s sovereignty and security, especially at this “very difficult time.”

US Senate deadlock over border security

Republican leader said that border security is the top priority for keeping America safe, and urged the Senate to act. He said that the Senate Republicans have no time to waste on convincing those who deny the facts on the ground.

Democratic leader countered that the Republicans are the only ones blocking the progress because of their extreme demands on the border. He said that the Democrats are willing to reach an agreement if possible.

Ukrainian president visits Washington

Zelenskyy arrived in Washington on Monday to deliver a speech at the National Defense University. He was welcomed by Defense Secretary Austin, who reaffirmed America’s security commitment to Ukraine as “unshakeable.”

Zelenskyy addressed the students and warned that delaying the approval of Ukraine aid benefits Putin and his “sick clique.” He said that America and other free nations need to be confident and assertive in their leadership, so that dictatorships lose their confidence and power to threaten freedom. He said that when the free world hesitates, that’s when dictatorships celebrate and commit their worst atrocities.

Biden administration announced a $175 million package of military aid to Ukraine under the Presidential Drawdown Authority – a fund that is running low, which is why the administration is asking for more from Congress.

Kirby, the Pentagon spokesperson, said on Monday that he “fully expects” more security assistance for Ukraine to be announced before the end of the month.

Zelenskyy seeks urgent U.S. aid amid congressional standoff