Acting Department of Homeland Security (DHS) Secretary Kevin McAleenan is warning of dire consequences at the U.S.-Mexico border if a request for additional funding is not approved by Congress.

“If we don’t get the supplemental funding, you’re going to see children backing up at the border in [Customs and Border Protection] facilities in conditions no American would be comfortable with in terms of how we care for children. Congress has to act on that funding," McAleenan told Hill.TV in an interview Monday evening.

He said that if his agency does not receive funding from Congress bolstering the ability to detain single adults, DHS will "either have to release adults" from detention "or we’re going to have to take cuts elsewhere in the Homeland Security budget in the middle of the year without planning. That means there’s going to be parts of the department that people rely on like TSA, like other elements of CBP."

He added that a "potential result" of such budgetary transfers from the Transportation Security Administration (TSA) could be longer wait times at airports.

"We’re going to have to transfer money from other accounts if we don’t get Congress’s help," he said.

The Trump administration last month requested an additional $4.5 billion to address border issues, with a bulk of the funding for the Department of Health and Human Services, which is charged with caring for unaccompanied migrant children who arrive at the border claiming asylum. Other funds would go toward single-adult bed space for Immigration and Customs Enforcement (ICE).

McAleenan said the only alternative for DHS if the funding is not approved is to hold unaccompanied children in detention cells at various points along the border. The cells are designed to detain adults for "very short periods of time," he said.

His remarks come amid a surge in illegal crossings at the U.S.-Mexico border. DHS apprehended more than 100,000 individuals in April. McAleenan did not have an official estimate yet for apprehensions in the month of May but told Hill.TV it will exceed April's record.

--Saagar Enjeti