WASHINGTON — The White House on Wednesday asked Congress for an additional $4.5 billion in emergency funding for the southern border.

None of the money being requested would be for construction of President Donald Trump's long-promised border wall, according to a senior administration official who requested anonymity to be able to discuss the details of the request.

Rather, the official said, the requested funds would be to deal with "the immediate humanitarian crisis."

That includes $3.3 billion for humanitarian assistance, such as food, clothing, diapers, transportation, bed space and increased shelter capacity for unaccompanied minors; $1.1 billion for operations and support to respond to the crisis at the border (including investigations related to smuggling); and another $178 million for additional support related to personnel and other resources.

The senior administration official said the humanitarian crisis at the U.S.-Mexico border has become "more dire" each day and that apprehensions are soon expected to surpass 1 million — more than double the number compared with 2018 levels.

The flow of migrants, the official said, is "rapidly overwhelming the ability of the federal government to respond.”

In a statement, House Appropriations Committee Chairwoman Nita Lowey, D-N.Y., said the Trump administration's "callous immigration policies" had "contributed to a humanitarian emergency on the border," adding that the funding request appeared to "double down on cruel and ill-conceived policies"

Nevertheless, Lowey added, House Democrats "will carefully review this request in its totality and, where possible, work with the Senate and the White House to make conditions at the border more humane.”

Trump's emergency request came just a day after acting Homeland Security Secretary Kevin McAleenan told a House committee that his department was running out of funds to deal with the growing number of migrants crossing the southern border.

U.S. officials encountered more than 103,000 undocumented immigrants crossing the country's southwest border in March, Homeland Security officials said last month — the highest levels in 12 years.

The request for funding was posted to the White House Office of Management and Budget's website Wednesday afternoon.