The bipartisan pull of corporate welfare—also known as the swamp—is powerful. Last week it swallowed up no less than Donald Trump and his fearless Environmental Protection Agency administrator, Scott Pruitt. They caved under pressure from the ethanol lobby and political extortion from Republican Senators Joni Ernst, Deb Fischer and Chuck Grassley.

Mr. Pruitt announced Thursday that EPA won’t reduce its proposed 19.24 billion gallon biofuels quota for 2018, and may even increase it. The EPA will further consider giving biofuels...