He and several of his former aides are now in the catbird seat when it comes to wrecking the EPA.

A year ago, Republican Sen. Jim Inhofe of Oklahoma was a joke. The former mayor of Tulsa was first elected to the Senate in 1994 and since then has built a reputation as an anti-scientific numbskull. From his perch at the Senate Committee on Environment and Public Works from 2003 on, he has championed the idea that human-caused climate change is a conspiracy of “far left environmental extremists.”

He has compared environmental advocates to the Nazis. In his tendentious 2012 book—The Greatest Hoax: How the Global Warming Conspiracy Threatens Your Future—he pounded on this theme with an ample collection of disinformation, misinformation, misinterpretation, exaggeration, fabrication, and concoction spiced with insipid personal attacks on Al Gore. In the mid-winter of 2015, he infamously tossed a snowball on the Senate floor to supposedly prove global warming isn’t happening.

Inhofe is still a joke. But he’s the one doing the laughing these days. That’s because the “Inhofe Brigade”—as it’s called by Stephen Brown, the vice president for government affairs at Tesoro, a major oil refiner—has landed in high places at the Environmental Protection Agency. Julie Eilperin and Brady Dennis report: