Hours after celebrating a rare moment of bipartisanship that saw the Senate pass a sweeping overhaul of the nation’s food safety laws, congressional backers of the legislation realized that it has a potentially fatal technical flaw and that they may not have time to fix it.

The Senate bill contains a section that authorizes the Food and Drug Administration to assess fees on food importers and food producers that have recalls or fail inspections. That’s considered a revenue-raising measure, and under the Constitution such legislation must originate in the House.

The bill, which passed 73 to 25, would impose new planning and record-keeping requirements on food producers and give the FDA power to recall tainted food and improve oversight of imported food.

The blunder sent congressional Democrats, who churned out a stream of news releases trumpeting the bill Tuesday, scrambling for a way to salvage the long-awaited legislation.

One possible scenario would be to pass the contents of the Senate bill as a House measure and send it back to the Senate for re-approval.

But a House Democratic staffer familiar with discussions on the issue said lawmakers haven’t decided what to do. A rapidly dwindling clock in the lame-duck Congress limits options.

The slower-moving Senate has a calendar stacked with big issues.

Senate Republicans on Wednesday served notice that they won’t agree to consider other legislation until Democrats agree to extend Bush-era tax cuts and fund government operations, further reducing the possibilities for a do-over on the bill.

Publicly, Senate Democratic aides put a positive spin on the embarrassing glitch.

The bill is not dead, insisted Max Gleischman, a spokesman for the bill’s sponsor, Sen. Richard J. Durbin (D-Ill.). “House and Senate leaders are working on a solution to the ‘blue-slip’ problem,” Gleischman said. “We anticipate a resolution to this issue and getting a food safety bill to the president’s desk before the end of the year.”