The airline trade group that supported a federal mask mandate for all air travelers has asked the Biden administration to end the mask requirement and eliminate other COVID-19 protocols for travelers.

Airlines for America, which represents American, Delta, United, Southwest, Alaska, JetBlue and other carriers, released a letter Wednesday addressed to President Biden, saying "the persistent and steady decline of hospitalization and death rates are the most compelling indicator that our country is well protected against disease from COVID-19."

"Now is the time for the administration to sunset federal transportation travel restrictions, including the international predeparture testing requirement and federal mask mandates," the letter said.

The U.S. Travel Association, which represents the country's travel industry, also issued a letter Wednesday, asking the Biden administration to end coronavirus testing for international travelers to the U.S. and mask mandates on flights.

The Centers for Disease Control and Prevention two weeks ago announced a one-month extension to the mask mandate for passengers on planes, buses, trains and transit hubs, to April 18. The CDC also said it was developing guidance to ease the mandate as soon as April.

In response to the extension, the Transportation Workers Union, which represents mechanics, baggage handlers, flight attendants and other transportation workers, said it supported any "federal guidance based on science" but noted that the mask mandate has led to harassment and assaults against flight attendants.

The unions that represent flight attendants and Airlines for America initially supported the decision made by the Biden administration — adopted soon after he took office in 2021 — to adopt a federal mask policy, requiring passengers to wear face coverings in airports and on airplanes except when eating or drinking. Violations are punishable by a fine of as much as $1,000 for the first offense and as much as $3,000 for repeat offenses.

Since September 2021, the Transportation Security Administration has imposed almost $400,000 in civil penalties against more than 600 passengers who refused to wear a mask on a plane.

Before the federal mandate, airlines adopted policies requiring passengers to wear masks but could only enforce the policies by threatening to ban violators from flying the carrier in the future.

Since the start of the pandemic, most of the incidents of unruly passengers on flights have been the result of disputes over the mask mandates, according to the TSA. Flight attendants say they have often been put in harm's way, trying to enforce the mask mandate on belligerent passengers, and ensure the safety of the passengers.

Earlier this week, a local union representing 16,000 flight attendants for Southwest Airlines said in a letter to Biden and Transportation Secretary Pete Buttigieg, among others: "Serving onboard during these contentious times and enforcing mask compliance is one of the most difficult jobs we have ever faced as flight attendants."

"We strongly believe it is now time to give our members and passengers the opportunity to choose if they prefer to wear a mask while flying," the union, TWU Local 556, said in the letter. "In the spirit of bringing normalcy back to our front lines as aviation's first responders, we ask that you consider lifting the federal mask mandate for airline travel and will move expeditiously to restore choice to aviation professionals and the flying public."