WASHINGTON (TND) - The Sunday after Thanksgiving is expected to be the busiest single travel day. However, a looming vaccine mandate deadline could make getting through the airport more difficult.

The mandate could prove disruptive if unvaccinated workers don't comply.

With the federal deadline just days away, a large chunk of airport workers are resisting the vaccine requirement, prompting warnings that staff shortages at TSA checkpoints will result in widespread delays for travelers.

“The return to travel and the rebound that we are going to see this Thanksgiving is remarkable,” said Doug Shupe with AAA.

With vaccinations easing concerns about airport travel, and ticket prices down 27 percent compared to last year, AAA predicts millions of Americans will fly to their destination this Thanksgiving.

“We have to keep in mind that there may be some delays at the airports,” Shupe said.

The White House's Nov. 22 vaccine mandate for federal employees hits just three days before Thanksgiving.

“What is TSA’s plan here? Are they going to discipline or even fire employees who are not fully vaccinated?” Rep. Carlos Gimenez (R-FL) asked.

Last month, TSA officials reported 60 percent of its workforce was vaccinated. While the agency would not release updated numbers, a spokesperson told The National Desk’s Ryan Smith, "we are still collecting vaccination data. While I can’t share data yet, the compliance rate is very high, and we do not anticipate any disruptions because of the vaccination requirements."

“I’m concerned that TSA is not adequately staffed to handle the rise in travelers that we will see in airports across the country over the next few weeks,” Rep. Gimenez said.

Lawmakers questioned travel industry leaders this week, asking if TSA is prepared to handle holiday crowds and potential chaos at America's airports.

“Challenges are going to be there,” said Everett Kelley with the American Federation of Government Employees.

Kelley's union represents more than 45,000 TSA employees. He admits that travel disruptions are likely if the vaccine mandate is enforced this month.

“We have not done an exceptional job in making sure that the workforce will replenish. We still have people that are in training that should be on the floor performing their jobs right now,” Kelley said.

Kelley and other union leaders are pushing the White House to delay the federal mandate until Jan. 4, the same date given to federal contractors.

There has been no word from the White House if that is on the tab.