The ethanol mandate, also known as the Renewable Fuel Standard, is an indefensible subsidy to an industry based in Iowa. The biggest ethanol players are power brokers in the state, which plays a central role in the nominating process of both parties. The result: a gravitational pull to pander that draws in even politicians who know better.

The RFS, created by George W. Bush, requires refiners to dilute their gasoline with ethanol, a fuel made from plants — mostly corn. This drives up demand for corn, and enriches the politically connected ethanol barons, like Iowa GOP powerbroker Bruce Rastetter. It also costs Americans money at the pump and in their grocery bills. It’s devastating for ranchers (it drives up the price of cattle feed) and environmentalists say it causes pollution and sucks up too much water.