OMAHA, Neb. (AP) — The Trump administration is following through on a plan to allow year-round sales of gasoline mixed with 15% ethanol. The Environmental Protection Agency announced the change Friday, ending a summertime ban imposed out of concerns for increased smog from the higher ethanol blend. The agency had proposed the change in March. The change also fulfills a pledge that President Donald Trump made to U.S. corn farmers, who see ethanol as an important driver of demand for their crops. Oil refineries have been seeking exemptions from government requirements to include ethanol in their fuel mixes.

Environmental groups contend the U.S. Clean Air Act prohibits year-round sales of E15, and court challenges are expected. Bill Wehrum, assistant administrator of the EPA’s Office of Air and Radiation, said today (Friday), the agency is prepared to win a court fight. Wehrum said in a conference call with reporters, that if the agency believed the change ran afoul of the Clean Air Act, “we wouldn’t have done it.”

Federal law for more than a decade has mandated that oil refineries mix ethanol into their fuel. The Trump administration’s former EPA chief, Scott Pruitt, had angered lawmakers, growers and ethanol processors in Iowa and other key election states by granting a spate of exemptions sparing refineries from that mandate. The dispute sparked a billboard campaign and at least one tractor rally by angry farmers in the Midwest last year, threatening to erode what has been a base of support for Trump.

According to Weddum, the change removes a barrier to wider sales of E15 and is expected to expand the market for ethanol — although immediate effects on the market are expected to be minimal. Only about 1,000 to 1,500 of more than 150,000 U.S. gas stations currently sell the higher-ethanol blend. “It’ll take some time” to see an overall jump in E15 sales, he said. Today’s (Friday’s) announcement was widely lauded by Midwest lawmakers, farm groups and the biofuel industry.

The EPA move also implements a regulatory change in the ethanol program intended to curb what the oil industry believes in price manipulation in the ethanol program. Wehrum said the regulatory change makes more transparent how ethanol tax credits are applied by ethanol blenders.