Texas sues to strike down the federal mask mandate for air travelers.

The Republican attorney general of Texas on Wednesday sued to strike down the Biden administration’s mandate requiring travelers to wear masks at airports, on airplanes and on commuter bus and rail systems.

The suit comes as many governors, including in states governed by Democrats, have been rolling back mask mandates for indoor public settings as infections from the Omicron variant of the coronavirus have plummeted following a record-setting surge last month. But forms of public transportation are regulated by the federal government.

Since it was first introduced a year ago, the federal mandate requiring travelers to wear masks has been extended several times, most recently until at least March 18. Brief breaks for eating and drinking are permitted. There are exemptions for travelers younger than 2 and for people with certain disabilities who cannot wear masks safely. Travelers who refuse to comply can be fined.

The suit by the Texas attorney general, Ken Paxton, was filed in federal court in Fort Worth. It argues that the mask mandate is unconstitutional and that the Centers for Disease Control and Prevention lacks the authority to impose the requirement. The Supreme Court recently declined to hear another case that sought to block the mandate.

Dr. Anthony Fauci, the nation’s top infectious disease expert, said in December that he did not believe the country was approaching a point where masks would no longer be necessary on planes. “Even though you have a good filtration system, I still believe that masks are a prudent thing to do, and we should be doing it,” he said.

The C.D.C. declined to comment on the suit in Texas.

Some airline executives have questioned the need for the mask mandate for air travel. The top executive of Southwest Airlines, Gary Kelly, said at a Senate hearing in December that he believed that masks do not add substantial protection in airplane cabins and that the filtration on planes was sufficient. Mr. Kelly, who testified unmasked and recently became the company’s executive chairman after many years as chief executive, tested positive for the virus later that week.