WASHINGTON – US Department of Homeland Security (DHS) Secretary Markwayne Mullin said Tuesday that his department will run out of money to pay employees' salaries the first week of May, as lawmakers have yet to resolve the prolonged shutdown of the department, which has stretched on for more than two months.

Mullin, who recently took office as the new head of DHS, told Fox News that the money to pay employees' salaries was coming from funds Congress allocated to DHS last summer via the One Big Beautiful Bill – a massive tax and spending bill.

Mullin, however, warned that DHS carries a substantial payroll obligation, and without renewed funding, remaining reserves are expected to run out early next month.

ALSO READ: US airport wait times stretch past 4 hours as shutdown cripples staffing

That means Transportation Security Administration (TSA) agents, who had been working without pay for over a month and just recently started receiving paychecks, would once again go without pay. Since the DHS shutdown, TSA officers have reported higher rates of absenteeism, contributing to longer-than-usual lines at airport security checkpoints.

"My payroll through DHS is just over 1.6 billion dollars every two weeks, so the money is going extremely fast and once that happens, there is no emergency funds after that," Mullin said. "I've got one payroll left and there are no more emergency funds, so the president can't do another executive order because there's no more money there."

READ MORE: US Senate Democrats reject Republicans' DHS funding proposal as shutdown continues

On March 27, US President Donald Trump signed a presidential memorandum to pay TSA workers, directing the Secretary of Homeland Security, in coordination with the Director of the Office of Management and Budget, to "use funds that have a reasonable and logical nexus to TSA operations" to provide TSA employees with compensation and benefits.

Trump's move came two days after Acting TSA Administrator Ha Nguyen McNeill told a House Homeland Security Committee hearing that wait times at US airport security checkpoints had reached the longest levels in the 24-year history of the TSA amid the prolonged DHS shutdown, with some exceeding four hours.

READ MORE: Trump threatens to deploy ICE agents for airport security over funding impasse

Democrats have called for reforms to Immigration and Customs Enforcement (ICE) operations following the fatal shooting of two US citizens by federal agents in Minneapolis in January. However, Republicans have repeatedly rejected their demands, resulting in a deadlock in negotiations. Against that backdrop, DHS funding expired on Feb 13.

Trump previously signaled support for a two-track strategy favored by Senate Majority Leader John Thune – funding most of DHS through a bipartisan deal with Democrats, followed by using the reconciliation process to secure funding for ICE and Border Patrol.

The president has also given lawmakers until June 1 to pass a funding bill, and Republicans are trying to put forward a funding package that could clear Congress.