The program requires inspections of U.S. catfish and requires non-U.S. catfish to be subject to an equivalent food-safety regiment before it can be imported. These requirements were put in place at the behest of U.S. catfish producers who were facing competition from Asia.

The House Republican agriculture bill would eliminate funding for the program, just as FSIS has put forward a proposed rule for implementing the inspection system. The rule was released in February, and FSIS was accepting public comments on its proposal through late June.

Republican and Democratic House members from Mississippi, Louisiana and Alabama can expected to argue against the bill for this reason, but are likely to face arguments that the program should be struck down as unnecessary.

In March, a bipartisan group of six senators argued that the program should be eliminated because it would hurt Vietnam's exports. Two of these senators — Sens. John KerryJohn KerryWeek ahead: Early questions for Trump on cybersecurity Kerry and his dog stroll through women's march Trump fails to mention Clinton in inaugural address MORE (D-Mass.) and John McCainJohn McCainIs McCain confident in Trump? ‘I do not know’ Schumer, Cardin to introduce legislation on Russia sanctions Graham says he will vote for Tillerson MORE (R-Ariz.) have strong interests in the economic development of Vietnam.

"The rule is likely to capture Vietnamese pangasius, which would shift these catfish products from the Food and Drug Administration (FDA)'s jurisdiction to USDA," their letter said. "Vietnamese companies would be forced to put into place processes the USDA deems 'equivalent' rather than use the FDA hazard analysis and critical control points system. That would impose an effective short and medium term ban on imports and a long term unnecessary new cost on imported catfish."

Other signatories to the Senate letter were Scott Brown (R-Mass.), Tom CoburnTom CoburnCoburn: Trump's tweets aren't presidential The road ahead for America’s highways Rethinking taxation MORE (R-Okla.), Mike CrapoMike CrapoLive coverage of Sessions confirmation hearing Senate rejects Paul's balanced budget Dems attack Trump SEC pick's ties to Wall Street MORE (R-Idaho) and Jeanne Shaheen Jeanne ShaheenTrump poised to reinstate 'global gag rule' on Roe v. Wade anniversary: report Trump country Dem takes risk by skipping swearing-in 5 billion reasons Rex Tillerson is wrong MORE (D-N.H.).