Despite stiff competition, Scott Pruitt, the administrator of the Environmental Protection Agency, is by common consensus the worst of the ideologues and mediocrities President Trump chose to populate his cabinet. Policies aside — and they’re terrible, from an environmental perspective — Mr. Pruitt’s self-aggrandizing and borderline thuggish behavior has disgraced his office and demoralized his employees. We opposed his nomination because he had spent his career as attorney general of Oklahoma suing the federal department he was being asked to lead on behalf of industries he was being asked to regulate. As it turns out, Mr. Pruitt is not just an industry lap dog but also an arrogant and vengeful bully and small-time grifter, bent on chiseling the taxpayer to suit his lifestyle and warm his ego.

Any other president would have fired him. Mr. Trump praises him. “Scott is doing a great job!” the president tweeted on April 7. He agrees with Mr. Pruitt on policy — indeed, many of the administrator’s worst moves have been responses to Mr. Trump’s orders. And — no small chiseler in his own right — Mr. Trump seems to care not a whit about Mr. Pruitt’s mounting ethical problems, which have lately reached a point where Mr. Trump’s chief of staff, John Kelly, has reportedly told the president that he should think seriously about letting Mr. Pruitt go.

These problems began innocently enough, with the revelation last year that Mr. Pruitt had ordered up a $43,000 soundproof phone booth for his office so that his employees could not overhear him. The nonpartisan Government Accountability Office said Monday that the purchase violated the law because the E.P.A. had not notified Congress before incurring the expense. But what seemed like early onset executive paranoia quickly metastasized. Citing security concerns, Mr. Pruitt insisted on flying first class, against government custom, and when possible on Delta Air Lines (not the federal government’s contract carrier), so that he could accumulate frequent-flier miles. He asked his staff to schedule trips back to Oklahoma so he could spend weekends at his home there. “Find me something to do,” he said, according to evidence presented to Congress by Kevin Chmielewski, who was the E.P.A.’s deputy chief of staff until he was forced to resign after raising objections to Mr. Pruitt’s excesses. Mr. Pruitt used his own security detail and hired private security guards during a trip to Italy — at a cost of $30,000 — when embassy guards were available free.