Berlin, Germany - Ukraine's President Volodymyr Zelensky on Sunday warned that a drop in aid from the United States to Kyiv would send a poor message, as President Joe Biden faces a Republican blockade on further support.

With an eye on US aid potentially diminishing, Zelensky urged Germany to use its economic weight to rally EU partners to give more to Kyiv in its fight against Russia.

"Passivity from the United States or the lack of support would be a bad signal," he told German national broadcaster ARD.

That is not right for anyone, Zelensky warned.

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"Germany can manage to consolidate the EU," he said in response to a question on whether he hoped that Berlin would take on a bigger role should help from the United States fall away.

"Many countries have important economic relationships with Germany, and their economy is dependent on Germany's decisions because Germany has a strong economy," he said.

In a separate interview on Wednesday, German Chancellor Olaf Scholz urged European nations to step up weapons pledges to Ukraine, raising the specter that help from the US, the biggest contributor, could end.

"Europe must do more to support Ukraine in the defense of its own country," Scholz told Die Zeit weekly, adding that the contributions that European nations have earmarked for 2024 so far are "not big enough."

Biden has made backing Ukraine a priority, and US weapons and financial assistance have been crucial in helping the pro-Western country battle against a far larger attacking Russian force.

But opposing Republicans have led a push to halt the effort, refusing to authorize new budget outlays unless the Democrats first agree to sweeping, tough new measures against illegal migration.

With the US in an election year that could again pit Biden against Donald Trump, Zelensky has warned that a Trump return to the White House would likely bring a "different policy" on the war.