President Joe Biden has invited his Ukrainian counterpart Volodymyr Zelensky to the White House on Tuesday, a spokeswoman said, as the US leader demonstrates his "unshakeable commitment" to embattled Ukraine after Congress blocked a request for aid.

The two leaders "will discuss Ukraine's urgent needs" as it fights off a Russian invasion, and "the vital importance of the United States' continued support at this critical moment," White House Press Secretary Karine Jean-Pierre said in a statement on Sunday.

The Ukrainian presidency said in a statement the meeting will focus on key issues such as "further defense cooperation between Ukraine and the United States, particularly through joint projects on the production of weapons and air defense systems, as well as the coordination of efforts between our countries in the coming year."

In a blow to Zelensky, Republican senators last week blocked $106 billion in emergency aid primarily for Ukraine and Israel after conservatives balked at the exclusion of immigration reforms they had demanded as part of the package.

It was a setback for Biden, who had urged lawmakers to approve the funds, warning that Putin would not stop with victory in Ukraine and could even attack a NATO nation.

The White House said the meeting came at a critical moment, "as Russia ramps up its missile and drone strikes against Ukraine."