A delegation of U.S. government officials is poised to begin meetings in South Korea next week to hash out international guidelines for countering the overuse of antibiotics in farm animals.

But the draft is already causing an uproar because it appears to be weaker than current U.S. policy, which allows such drugs to prevent or treat diseases in livestock but not for growth promotion.

On Friday, four U.S. senators and one House member, all of them Democrats, raised concerns about the draft in a letter to Agriculture Secretary Sonny Perdue and Food and Drug Administration Commissioner Scott Gottlieb, whose employees are participating in the negotiations.

“We urge you to ensure that the U.S. opposes the use of medically important antibiotics in animals for growth promotion without exception when this committee meets next week,” says the letter, which is signed by Senators Dianne Feinstein, Elizabeth Warren, Richard Blumenthal and Kirsten Gillibrand and Representative Rosa DeLauro.