WASHINGTON, United States -- The White House is asking Congress for $22.5 billion in emergency funding to combat Covid-19 after exhausting nearly all the money set aside for the pandemic, officials said Thursday.

Cash previously greenlit by lawmakers -- including the $1.9 trillion American Rescue Plan -- has all but dried up and initiatives such as free Covid testing will end "this spring" without more money.

Roughly $4 billion would go to global vaccination efforts, while the health department would spend the rest on testing, antiviral pills, monoclonal antibodies and research on new vaccines.

Shalanda Young, the Office of Management and Budget's acting director, made the request in a letter sent to Capitol Hill late Wednesday.

"Resources from the prior Covid response bills enabled us to get over 215 million Americans fully vaccinated, make one billion tests available to Americans for free, order 20 million antiviral treatment pills... and commit to donating 1.2 billion vaccines to the world," Young said in a statement Thursday.

"They also let us respond forcefully to the Delta and Omicron surges -- but now, nearly all of these funds have been used." The request comes as lawmakers haggle over a broader aid package -- including a White House request for $10 billion to address the Ukraine crisis -- that they hope to include in a deal to fund the government for the rest of the financial year.

The money to run federal agencies runs out on March 11 and party leaders in the House and Senate hope to have the bill passed before that date.

While there is strong cross-party support for Ukraine funding, the additional Covid money is set to be controversial.

Mitt Romney and 35 fellow Senate Republicans asked Wednesday for a "full accounting" of the $6 trillion already approved by Congress to respond to the pandemic.

"While we have supported historic, bipartisan measures in the United States Senate to provide unprecedented investments in vaccines, therapeutics, and testing, it is not yet clear why additional funding is needed," they said in a letter to President Joe Biden.

"Since passage of the American Rescue Plan in February, questions are mounting about where exactly the additional money has gone," the senators added.