If the United States postpones military aid to Ukraine, there is a “big risk” the country could lose its war with Russia, Ukrainian President Volodymyr Zelenskyy’s chief of staff Andriy Yermak said Tuesday. 

Speaking at the U.S. Institute for Peace during a visit to Washington, Yermak said failure by Congress to approve more aid to Ukraine could make it “impossible” to liberate more territory captured by Russia and “give the big risk to lose this war.”

“If the help which (is) now debating in Congress will be just postponed. … It gives the big risk that we can be in same position (where) we’re located now,” said Yermak, speaking in English.

“That is why it is extremely critically important that this support will be voted and will be voted as soon as possible,” he said.

Yermak’s remarks came as Zelenskyy was due to speak to lawmakers in a confidential video call, in a bid to appeal to Congress to back a proposed aid package requested by the Biden administration.

Ukraine greatly appreciated the U.S. and European support provided since Russia invaded Ukraine in February 2022, Yermak said. But Kyiv still needs more weapons to defend itself and to protect civilians who have returned to areas once occupied by Russian troops, including long-range missiles and air defense systems, Yermak said.

Ukraine has shown that it is able to make good use of the weapons and ammunition delivered so far, he added. 

Ukrainians still had a strong incentive to carry on the war to secure their “freedom,” he said. 

“It’s very difficult for our people but Ukrainians are still very motivated,” Yermak said. “Our people believe and are sure that we will win.”

Yermak said he was meeting with members of Congress as well as with White House and State Department officials to appeal for a renewal of U.S. assistance.

On Monday, the administration warned lawmakers that by year’s end Washington would run out of money to deliver more weapons to Ukraine.

The Biden administration has asked Congress for more than $105 billion to fund assistance to Ukraine, Israel and U.S. border security measures. But Republicans in the House have rejected the request.

Senate Majority Leader Chuck Schumer, D-N.Y., said on Monday that democracy around the world would be at risk if Russian President Vladimir Putin was allowed to prevail against Ukraine.

“We can’t ever put a price on defending democracy in its hour of need, because if Ukraine falls, Putin will keep on going,” Schumer said.

“Autocrats around the world will be emboldened. Democracy, this grand and noble experiment, will enter an era of decline.”