Perkins Cole, a law firm representing small U.S. refineries has urged the Environmental Protection Agency to keep refiners’ applications for waivers from the Renewable Fuel Standard secret from USDA, arguing that the petitions include confidential business information, according to BusinessWorld.

A dozen Republican senators, led by John Barrasso of Wyoming, have called on President Donald Trump to keep Agriculture Secretary Sonny Perdue from intervening in government decisions over granting oil refineries exemptions from biofuel-blending quotas. The senators say federal law gives Perdue no role in the decision, according to Bloomberg.

The issue that pits the oil and biofuel lobby against one another is the 14-year-old Renewable Fuel Standard. The EPA establishes standards for the annual use of biofuels under the RFS. Biofuel proponents argue the administration has handed out waivers too freely and is undermining domestic demand, Bloomberg reports.

In its letter, Perkins Cole wrote that refiners feared USDA would share the confidential information in the applications with the agricultural community, harming the refiners, according to Grain News.

Perdue has often sided publicly with farmers on the issue of biofuel waivers and told farmers in Iowa that he was working to devise a fix, according to WTVBAM.com.

Related:NCGA targets EPA RFS waivers in new campaign