"The airlines are not listening to their passengers," Sen. Edward Markey, D-Mass., said in an interview on Wednesday. "They're going to wind up paying a price for this in the next piece of legislation which we pass."
U.S. carriers have secured almost $60 billion from the federal government in cash grants and loans. In exchange, the airlines agreed to not lay off employees through September, to place limits on executive compensation for two years and to eliminate stock buybacks for at least a year.
Markey said airlines are being "greedy" by refusing to issue refunds for canceled flights.
"Passengers need to stay alive the same way that the airlines now can stay alive because of the federal taxpayer," Markey said.
A little over a week ago, Markey and eight other Democratic senators sent letters to all the major U.S. airline CEOs, urging them to issue refunds. The senators asked for a response by Tuesday.
As of Wednesday morning, lawmakers hadn't received enough responses to determine whether or not "the industry is going to comply," Markey said. "A passenger in the era of the Coronavirus pandemic should not have to have a voucher for a future trip. That passenger needs the money in their pocket right now to pay for food, to pay for rent, to pay the mortgage."
On Monday, a police officer from Minnesota, Jacob Rudolph, filed a lawsuit against United Airlines over a rejected ticket refund claim.
A United spokesperson told ABC News that the company was served with the complaint on Tuesday evening and currently is reviewing it. The spokesperson said United's policy on refunds is that if the airline changes a flight and can't get a passenger to their destination within six hours, that customer is eligible for a refund.
According to Rudolph, United offered to rebook his flight or issue him a ticket credit for travel within one year of the issue date. United and other major U.S. airlines have since announced they are extending voucher expirations for up to two years.
A class-action suit was filed just three days after the Department of Transportation told the airlines that they're obligated to provide a "prompt refund” to passengers whose flights were affected by the outbreak.
"The Department is receiving an increasing number of complaints and inquiries from ticketed passengers, including many with non-refundable tickets, who describe having been denied refunds for flights that were canceled or significantly delayed,” DOT said in a statement. "In many of these cases, the passengers stated that the carrier informed them that they would receive vouchers or credits for future travel."
In an attempt to weather the crisis, the airline industry has taken unprecedented measures such as slashing flights, cutting executive pay, offering employees unpaid leave and parking hundreds of aircraft.
At Delta Airlines, 30,000 employees -- about one-third of the company's global work force -- have volunteered to take unpaid leave, according to an internal memo from CEO Ed Bastian to employees.
Bastian said the airline is burning more than $60 million every day, and that without the company's self-help actions the funds received from the stimulus package "would be gone by June."