The Trump administration has already reassigned agents from Immigration and Customs Enforcement to at least 14 airports nationwide to help manage lines and support security screening efforts.

"We're going to send in the National Guard, if we need to," Trump said Wednesday at a fundraiser for congressional Republicans.

Transportation Security Administration workers have gone without full paychecks since the DHS shut down Feb. 14, and officials say absences have increased as the congressional fight drags on. More than 450 TSA officers have quit altogether since the partial shutdown began, according to DHS.

Lawmakers in stalemate over DHS funding

More than 40 days into the shutdown, negotiations over DHS funding remain deadlocked. The impasse stems from congressional disagreements over ICE and Customs and Border Protection following the killings of Alex Pretti and Renee Good in Minneapolis.

Republicans argue they've met Democratic demands and accuse them of shifting the goalposts, while Democrats say their position has not changed. With Congress set to begin a two-week recess Friday, pressure is mounting to reach a deal.

DHS officials warn that the longer the shutdown lasts, the harder it will be to recruit and retain TSA workers, raising concerns about lasting effects on airport operations nationwide.

Record TSA wait times at airports

Travelers are facing security lines stretching for hours, with DHS calling them the longest wait times on record. The delays come as thousands of TSA officers continue to miss work.

On Tuesday, more than 3,000 TSA employees — more than 11% of the workforce — called out.

Absentee rates were even higher at some major airports, with nearly 40% of TSA staff absent at New York's JFK Airport and close to 50% not reporting to work at Houston's Hobby Airport.

TSA officials expect the situation to worsen as workers miss a third paycheck by the end of the week.

"As they continue to miss paychecks, they won't be able to cover basic needs like rent and food," said acting Deputy TSA Administrator Adam Stahl. "It will become increasingly difficult for them to come to work, leading to more absences and even longer lines."

Assaults on TSA workers up 500% since partial shutdown began

Those who do show up for work are facing the wrath of upset travelers, with assaults on TSA workers up 500% since the partial shutdown began, acting TSA administrator Ha Nguyen McNeill told lawmakers on Wednesday.