A serious constitutional snafu is threatening to derail pending food safety legislation, which passed the Senate by a 3-1 margin early Tuesday.

The FDA Food Safety Modernization Act, S. 510, would be the most significant update of food safety laws in over seven decades, but it has become clear that the Senate made a potentially critical error by including a provision that would allow the FDA to impose fees on importers, and on companies whose food is recalled because of contamination.

Article 1, Section 7 of the U.S. Constitution says all revenue-raising measures must originate in the House. This error will almost certainly mean that the legislation will have to be reconsidered in the Senate, a major setback considering the precious floor time it could take to jump though the necessary procedural hoops: namely circumventing Sen. Tom Coburn’s (R-OK) filibuster threat.

The way forward for the beleaguered legislation–which seemed to catch a big break with its 73-25 passage in the Senate this week–remains highly uncertain.

The Hill reported Wednesday that senior Democrat leadership aides still believe they can take another vote. “We are confident that we can work with our House colleagues to find a path forward and get this bill to the president before the end of the year,” one aide told the Capitol Hill newspaper.

As J. Taylor Rushing and Mike Lillis aptly noted yesterday: “While the changes themselves might not be too complicated, the Senate will have a much tougher time passing the bill again. Coburn is expected to object to passage by unanimous consent, as he has in the past, and Senate Republican leaders say their caucus won’t vote on any bills until the expiring tax cuts are dealt with.”

House Majority Leader Steny Hoyer (D-MD) said Wednesday the House was prepared to move on the Senate bill if the constitutional issues were resolved.

“While we think our bill was much better, we’re prepared to pass a bill along the lines that they passed,” said Hoyer. “Unfortunately, they passed a bill which is not consistent with the Constitution of the United States.

“It has to be a House bill, because it has revenues in it. … That’s a constitutional requirement. … The Senate knows this rule, and should follow this rule. … Nobody ought to be surprised by this rule,” the Hill reported Hoyer as saying.

Hoyer said he met with Sen. Tom Harkin (D-IA) to address the constitutional difficulties in an effort to move the bill forward before the end of the dwindling lame duck session.

“I’m hopeful that we will pass that back to the Senate in a corrected version … I presume they’ll be able to pass it — it passed pretty handily in the Senate,” said Hoyer.

Whether Senate Democrats will allow the food safety debate to consume any more floor time with so many other high-level political priorities, like the Bush tax cuts, the defense authorization, which includes a provision to repeal “don’t ask, don’t tell,” remains to be seen.