Democrats are ratcheting up the pressure on airlines to give back the windfall they've reaped by raising fares during the tax holiday brought by the partial shutdown of the Federal Aviation Administration.
Two groups of senators sent letters Friday to airline CEOs and other industry officials demanding airlines return the money they've pocketed to passengers.
But it's unclear if Democrats have enough leverage to force the issue. Kenneth Quinn, a former FAA chief counsel, said any attempt to retroactively force airlines to give up revenue from fare increases is likely to be successfully challenged in court.
The FAA's operating authority -- and airlines' authority to collect $30 million a day in federal ticket taxes -- expired last week as the result of a legislative stalemate between the House and Senate.