The White House sent a $45.8 billion supplemental spending request to Congress on Tuesday night to bolster funding for federal agencies’ response to the COVID-19 pandemic.

Administration officials stressed that the appropriations request is completely separate from a $1 trillion economic stimulus package that Treasury Secretary Steven Mnuchin is working on with Senate Republicans. The money is needed to deal with a surge in confirmed cases that is stretching the U.S. medical system, officials said.

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The White House budget office’s acting director, Russell Vought, wrote in a letter accompanying the request that the funding is needed because “with the pandemic growing, resource needs have also grown.” Vought wrote that the “unprecedented mobilization the Administration has achieved has forced agencies to incur unanticipated costs,” which he said “must be met with a legislative response to ensure full operational capacity.”

The Office of Management and Budget also submitted amendments to its fiscal 2021 spending request, increasing its asks for the Centers for Disease Control and Prevention and National Institute of Allergy and Infectious Diseases, two agencies at the forefront of attempting to contain and treat COVID-19, by a combined $1.8 billion.

The Veterans Health Administration accounts for the bulk of the supplemental request, or $16.6 billion. Officials there expect a major increase in patient care related to the coronavirus. Most of the new veterans health care request would be for treatments, testing and things like temporary intensive care unit beds, though there’s also $1.2 billion for health information technology and telehealth initiatives.

Other departments receiving major portions are Health and Human Services with $11.5 billion; Defense, which would receive $8.3 billion; and Homeland Security, which would get $3.2 billion.

Of the HHS money, $5.2 billion would go toward research and development into vaccines, drug treatments and testing, and the CDC would receive $3.4 billion to build out laboratory capacity and state and local preparedness and response efforts.

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The DHS portion of the request could prove contentious with some Democrats: The administration wants more than $800 million for Customs and Border Protection and Immigration and Customs Enforcement, including funding for migrant quarantine facilities. ICE would get money for charter flights — needed because commercial airlines are cutting back capacity — to “continue repatriating aliens ordered removed and reduce the need for additional beds.”

There’s also a request for a new $3 billion account for unspecified purposes that would be directly managed by Vought. The new “Unanticipated Needs” account, which would be modeled after a similar fund set up after the Sept. 11 terrorist attacks, could raise some eyebrows on Capitol Hill.

“This fund would provide the Director of OMB the authority to transfer funds to Federal Departments and agencies to cover unanticipated costs associated with mitigating the impacts of the COVID-19 virus,” the request states.

In addition, the White House is seeking $500 million to cover Amtrak’s losses in the first half of 2020; the passenger rail service has been expecting steep losses due to travel cutbacks.

Other funding requests of note include:

• $2 billion to replenish the Federal Emergency Management Agency’s Disaster Relief Fund; President Donald Trump on Friday announced he was ready to tap $50 billion in FEMA funding for extraordinary public health needs.
• $40 million for student borrowing costs, including Trump’s deferral of interest payments on federally backed student loans.
• $400 million for the Department of Housing and Urban Development to support increased needs at homeless shelters.
• $73 million to evacuate thousands of Peace Corps volunteers still at their overseas posts.
• $241 million for the IRS to improve taxpayer services and handle the 90-day delay in the regular April 15 tax-filing deadline announced by the Treasury Department.

The request includes funds in smaller amounts for multiple other federal agencies.

The new funding would come on top of $8.3 billion Congress provided in early March, largely to help public health agencies prepare, finance the research and development of vaccines and new drug treatments, stockpile medical supplies and help overseas disease-fighting efforts.

It wasn’t clear how quickly Congress would act on the new funding request. The Senate is working on a House-passed bill to help individuals and families affected by illness and work stoppages, and several committees are already engaged in working on the broader stimulus package Mnuchin discussed Tuesday.

Peter Cohn contributed to this report.