DES MOINES, Iowa (AP) — Ethanol production has become a key issue in Iowa’s closely matched U.S. Senate race, with both candidates pledging support for an industry that is important to the state’s corn-powered agricultural economy.

Democrat Bruce Braley and Republican Joni Ernst have both sought to assure voters they oppose a proposal from the Environmental Protection Agency that would reduce the amounts of ethanol and other biofuels that must be blended into gasoline.

Braley is touting his efforts to halt the changes. Ernst argues she supports maintaining the existing standard — known as the Renewable Fuel Standard — though she has taken questions over statements that she is she is opposed to subsidies from a “philosophical standpoint.”

The Iowa Farm Bureau’s political committee endorsed Ernst, while the Iowa Corn Growers Association PAC backed Braley.