DES MOINES, Iowa (AP) — Sen. Charles Grassley of Iowa, a leading supporter of corn-based ethanol, says he’ll call for Environmental Protection Agency Administrator Scott Pruitt’s resignation if Pruitt doesn’t work to fulfill federal ethanol mandates. Grassley is showing frustration with Pruitt’s lack of action to uphold the Renewable Fuel Standards law. On a conference call with agriculture reporters Tuesday Grassley said Pruitt had better follow through with ethanol mandates or “I’m going to be calling for Pruitt to resign because I’m done playing around with this.”

Grassley says President Donald Trump has committed to upholding 15 billion gallons of ethanol to be mixed into the nation’s fuel supply but Pruitt has been allowing refineries to evade some of that commitment by issuing waivers. Grassley says that has reduced ethanol content to 13.8 billion gallons.