Major airline CEOs have urged the US Congress to end the government shutdown that has left airport workers without pay, warning travellers could face more delays.

American Airlines, Delta, Southwest, and JetBlue are among the airlines that have written to lawmakers to demand that funding be restored to the Department of Homeland Security (DHS), which oversees the TSA.

The DHS has gone without funding since February, after Congress failed to reach a funding agreement. The Trump administration has blamed delays on Democrats, who declined to pass funding without immigration reforms.

"Once again, air travel is the political football amid another government shutdown," the CEOs wrote.

"First, leaders should immediately come together to reach an agreement ​to fund the Department of Homeland Security," they added. "Then they need to act so this problem never happens again."

The letter also urged Congress to pass legislation guaranteeing that air traffic controllers are paid regardless of changes to government funding.

In their letter, the CEOs said it's "difficult, if not impossible" for TSA workers to "put food on the table, put gas in the car and pay rent" without pay.

TSA workers missed their first full paycheck on Friday, but they are required to continue working as they are considered essential workers. It is possible they will receive back pay or compensation once the shutdown ends.

More than 300 TSA employees have quit, DHS said on Friday, and the BBC's US partner, CBS News, found call-out rates have more than doubled since the funding lapse began.

The staffing shortage, along with severe weather warnings and spring break, led to some travel disruptions over the weekend.

In Austin, Texas, wait times exceeded 100 minutes. Travellers at Fort Lauderdale International Airport and Hartsfield-Jackson Atlanta International Airport also experienced long queues.

Austin-Bergstrom International Airport told travellers on Monday to arrive at least 2.5 hours before domestic flight departures due to delays.

Meanwhile, Denver International Airport, Seattle-Tacoma International Airport and Harry Reid International Airport in Las Vegas have asked travellers to donate items or gift cards to TSA employees working without pay.

Antoinette Wade, President of American Federation of Government Employees (AFGE) 1047, a union that oversees 13 airports in Louisiana and Mississippi, said she was concerned about the toll the shutdown was having on TSA workers.

"In any other job setting, this would be inexcusable; it doesn't make it excusable because we work for the federal government," she said.

US President Donald Trump on Sunday and urged TSA agents to "go to work", writing on Truth Social: "I promise that I will never forget you!!!"

The partial shutdown began on 14 February, when Democrats refused to fund the DHS without more restrictions on US Immigration and Customs Enforcement (ICE), another agency that falls under the department's jurisdiction.

ICE will not be significantly affected by the shutdown because Congress already provided the agency funding.

But Democrats have been demanding reforms to the agency as part of any funding deal after federal agents killed two Minneapolis residents, Alex Pretti and Renee Good, who were protesting against the Trump administration's immigration raids in Minnesota in January.

They have asked that the DHS bar immigration agents from wearing face masks, provide better identification for officers and tighten rules for obtaining warrants.