The top ranking Democrat on the Senate's transportation committee is warning airlines not to add extra fees for checked baggage over the holidays, citing reports that at least two budget carriers are tacking onto their regular luggage fees.

Spirit and Frontier Airlines have said they are charging extra fees for checked luggage for flights between Thanksgiving and New Years, according to a recent report from Time Magazine.

Sen. Bill Nelson Clarence (Bill) William NelsonDemocrats sound alarm on possible election chaos Trump, facing trouble in Florida, goes all in NASA names DC headquarters after agency's first Black female engineer Mary W. Jackson MORE (D-Fla.) said Friday that other airlines should not follow suit with their low-fare competitors.

ADVERTISEMENT

"These increased surcharges fly in the face of declining fuel costs and appear focused on increasing profitability on the backs of American families," the Florida Democrat, who is the top ranking Democrat on the Senate Commerce, Science and Transportation Committee, wrote.

"That’s why I am seeking an assurance from your company that you will not impose a holiday surcharge on baggage fees," he continued. "Furthermore, if your company does plan to impose holiday surcharges, I request that you rescind those plans immediately."

Airlines have come under fire for their bag fees before, from both lawmakers and consumer groups.

Passenger advocacy groups have attributed the increase in the amount of carry-on luggage to the fees for checked baggage that have been implemented by almost every U.S. airline in recent years. They say passengers are carrying on bags that they would have previously checked to their destinations to avoid the fees.

Airlines have defended the bag fees, saying it allows passengers to choose how much luggage they want to bring on flights.

Nelson said he is planning to offer legislation to place limits on the amount of extra fees airlines can charge passengers.

"In August, Senate Commerce Committee minority staff released a report that found ancillary fees, such as change and cancellation penalties and preferred seating fees, were increasingly keeping consumers in the dark about the true cost of air travel," he wrote.

"The report made a number of recommendations, including one requiring ancillary fees to have a clear connection between the cost incurred by the airline and the fee charged," Nelson continued. "I hope to include many of the report’s recommendations in legislation reauthorizing the Federal Aviation Administration that’s expected to come before the Senate next year."

Airlines collected $3.5 billion from baggage fees in 2014, according to statistics that have been compiled by the Department of Transportation.