By Chris Prentice, Reuters.

A coalition of trade groups representing oil, biofuels and other interests pressed the U.S. government on Thursday to deny requests to tweak the country's biofuels program, the latest in a series of political maneuvers that have roiled markets.

Some 15 trade groups including the American Petroleum Institute (API), Biotechnology Innovation Organization and the Association of American Railroads wrote a letter urging the U.S. Environmental Protection Agency's (EPA) new chief Scott Pruitt to deny requests to tweak the program. Those requests came from groups including Valero Energy Corp and Delta Air Lines Inc's Monroe Energy LLC.

Some industry groups have been concerned that the Trump administration may be reviewing potential changes in the program to shift the onus of blending biofuels into gasoline away from refiners further down the supply chain to gasoline marketers.

The change could require companies such as retailers who sell gasoline to shoulder that load, which would provide relief to refiners including Valero and CVR Energy Inc. The change is opposed by biofuels companies and integrated oil companies, which say it will complicate the program.