WASHINGTON (AP) — President Joe Biden has invited the top four congressional leaders and other lawmakers to the White House on Wednesday as members have struggled to reach agreement on U.S. aid for the Ukraine war. Republicans have insisted on pairing it with their own demands for securing the U.S. border.

A bipartisan group of negotiators in the Senate has been working for weeks to find an agreement that would provide wartime money for Ukraine and Israel and also include new border policy that is strong enough to satisfy Republicans in both chambers. The talks appeared to slow last week as senators said significant disagreements remained.

White House press secretary Karine Jean-Pierre said Tuesday that the lawmakers — including Speaker of the House Mike Johnson, R-La., House Democratic Leader Hakeem Jeffries, D-N.Y., Senate Majority Leader Chuck Schumer, D-N.Y., and Senate Republican Leader Mitch McConnell, R-Ky., — were invited to meet with Biden "to discuss the critical importance of his national security supplemental requests."

Biden's top budget official warned earlier this month about the rapidly diminishing time that lawmakers have to replenish U.S. aid for Ukraine. Shalanda Young, the director of the Office of Management and Budget, stressed that there is no avenue to help Ukraine aside from Congress approving additional funding to help Kyiv as it fends off Russia in a war that is now nearly two years old.

While the Pentagon has some limited authority to help Kyiv absent new funding from Capitol Hill, Young said at the first of the month, "that is not going to get big tranches of equipment into Ukraine."

White House national security adviser Jake Sullivan and U.S. Secretary of State Antony Blinken met with Ukraine President Volodymyr Zelenskyy at the World Economic Forum's annual meeting in Davos this week. In an appearance Tuesday following the meeting, Sullivan said he remained confident the Biden administration would come to an agreement on Ukraine aid in the coming weeks.

"What I will say is that we've got to be able to deliver the necessary resources to Ukraine for the weapons that it needs to be able to achieve the results that it needs," Sullivan said in conversation with Børge Brende, president of the World Economic Forum. "I continue to believe and express confidence that we will…after a lot of twists and turns ultimately get there."

Biden has faced staunch resistance from conservatives to his $110 billion request for a package of wartime aid for Ukraine and Israel as well as other national security priorities. Republicans have demanded that the funding be paired with significant border security changes.

The Biden administration has been directly involved in the talks as the president tries to both secure support for Ukraine's defense against Russia and also make progress on border policy.

Biden, who is up for re-election this year, has come under significant criticism for his handling of the historic number of migrants seeking asylum at the U.S. border with Mexico.

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Associated Press writers Aamer Madhani, Zeke Miller and Seung Min Kim contributed to this report.