The embattled and embarrassed transportation secretary, Pete Buttigieg, is now drawing fire from key Democrats in Congress, demanding that he do more on behalf of beleaguered airline passengers who face thousands more canceled flights over the coming July 4th weekend.

As we have reported, the transportation secretary has residual authority to crack down on the airline practice of having insufficient crew staffing to meet the schedules they publish and the tickets. That—and not weather delays—is the prime cause of last-minute flight cancellations.

Yesterday, Sen. Bernie Sanders (I-VT), chair of the Senate Budget Committee, put out a tough statement calling on Secretary Buttigieg to take urgent steps to protect passengers and crew members, including requiring airlines to promptly refund passengers for flights that have been delayed over an hour; imposing fines on airlines for flights that are delayed more than two hours; and imposing fines on airlines for scheduling flights that they are unable to properly staff, at a rate of $55,000 per passenger, which is high enough to force the airlines to take the much cheaper step of actually hiring enough people to fly the planes.

Today, Sanders was joined by Rep. Ro Khanna of California, who serves on the House Oversight Committee and is deputy whip of the Congressional Progressive Caucus. In a letter obtained exclusively by the Prospect, Khanna wrote to Buttigieg: "The Department’s incremental response so far has been lacking the urgency, imagination, and boldness to meet the moment and needs of the American people."

Khanna credited the Prospect’s reporting for raising the visibility of the issue of airlines’ abuses and Buttigieg’s feeble responses. He told me: "Buttigieg needs to make clear that he has the authority to go after the airlines for unfair and deceptive practices. He needs to lay out a framework for what the consequences will be for canceled flights, understaffing, and misrepresentations to passengers."

Khanna added that, as a senior member of the Oversight Committee, he will be pursuing hearings to call airline executives and the transportation secretary. "DOT’s approach has been way too timid," he added. "The administration should realize that this type of enforcement action will rally people to appreciate what their government can do on their behalf. This is a solvable problem."

Read the letter from Rep. Khanna here.