The Biden administration should intervene to deter Colombia from launching an investigation into U.S. subsidies for corn growers, says a bipartisan group of lawmakers who argue that new duties could imperil a top export market.

“Maintaining market access is critical to the interests of American farmers,” the 39 lawmakers wrote to Secretary of Agriculture Tom Vilsack and U.S. Trade Representative Katherine Tai. They were led by Senate Finance Committee members Todd Young, R-Ind., and Michael Bennet, D-Colo., and House Ways and Means Committee members Adrian Smith, R-Neb., and Dan Kildee, D-Mich.

The lawmakers were responding to reports that the Colombian government is weighing an investigation into U.S. corn subsidies. A similar probe earlier this year into U.S. milk powder resulted in countervailing duties on products destined for Colombia. The lawmakers argued that significant duties on corn exports could lead to U.S. growers losing access to an export market worth around $1.14 billion.

“We urge you to elevate the existing bilateral dialogue on this issue to prevent any arbitrary trade-restrictive measures,” the lawmakers wrote. “American farmers cannot afford to lose such a vital export market, especially when access to the top U.S. corn export market, Mexico, is already at risk,” the lawmakers added, referring to a U.S.-Mexico dispute over the country’s ban on genetically modified white corn.

Senate Finance Committee Chair Ron Wyden, D-Ore., and ranking member Mike Crapo of Idaho, were also among the signatories, as was incoming Senate Agriculture ranking member Amy Klobuchar, D-Minn.