An employee with the Transportation Security Administration (TSA) checks the documents of a traveler at Reagan National Airport in Washington, U.S., January 6, 2019. REUTERS/Joshua Roberts

WASHINGTON (Reuters) - The chairman of the U.S. House Homeland Security committee has asked the Trump administration how it is ensuring adequate staff at airports as some transportation employees fail to show up for work due to a partial U.S. government shutdown.

Representative Bennie Thompson, a Democrat, also asked the Transportation Security Administration (TSA) for the exact number of employees who are calling in sick and if the agency has a contingency plan for future mass absences or resignations of its screeners.

More than 50,000 TSA officers are working without pay during the shutdown that began Dec. 22. They will be paid for back wages when the government reopens.

“TSA officers are among the lowest paid federal employees, with many living paycheck-to-paycheck,” Thompson wrote in a letter Monday released by his office.

“Officers may not be able to pay for rent, child care, and other necessities if their paychecks do not arrive on time... It is only reasonable to expect officer call outs and resignations to increase the longer the shutdown lasts, since no employee can be expected to work indefinitely without pay.”

TSA said it would respond to the letter but added that “publicly providing numbers of those who call out sick represents a security concern. That said, we’re not seeing significant numbers of people calling out and have not seen operational impacts.”

On Monday, TSA said it had screened approximately 2.22 million passengers on Sunday and 99.8 percent of passengers waited less than 30 minutes.

The White House continues to grapple with a partial federal shutdown that began 16 days ago over President Donald Trump’s demand for funding for a wall along its the country’s border with Mexico.