Andrew R. Wheeler, the Environmental Protection Agency administrator, visited the Monroe Energy refinery in Trainer on Monday and delivered a 10-minute address touting the Trump administration’s energy policy without once mentioning the reason he was invited to Delaware County: the Renewable Fuel Standard (RFS).

The EPA chief took a quick tour of the refinery, owned by Delta Air Lines, and met with refinery workers, industry leaders and U.S. Sen. Patrick Toomey (R.Pa.,). Toomey invited Wheeler to the plant as part of his effort to weaken the RFS, which mandates the blending of biofuels such as ethanol into motor fuel. Oil refiners dislike the RFS because it reduces petroleum’s market share of motor fuel.

Though Wheeler avoided talking about the RFS during a brief address with about 200 refinery workers assembled in the refinery’s fire station, he told reporters afterward that the EPA is now considering applications from smaller refiners for partial waivers of their ethanol obligations. Ethanol producers object to the waivers, saying they would weaken the government’s commitment to farm states that produce corn used to make ethanol.

The RFS is a sensitive topic for the Trump administration, which has tried to walk a tightrope between oil producers and farmers, according to Sandy Fielden, a Morningstar analyst who on Monday posted a report exploring the administration’s predicament trying to placate competing oil and ethanol interests.