If you want to get a sense of Donald Trump’s deepening dementia, look no further than his self-annihilating vendetta against Federal Reserve Chair Jerome Powell. As you may recall, Powell’s term as chair expires soon, on May 15, but his term as a Fed governor continues through January 2028.

Trump has appointed a successor, former Fed governor and investment banker Kevin Warsh, who would ordinarily have his confirmation hearing next week. Warsh would then become Fed chair, succeeding Powell, who would likely leave the Fed entirely. So the quickest way for Trump to oust Powell would be just to let Warsh’s confirmation proceed and avoid screwing it up.

But Trump being Trump, his vanity, rage, and muddled thinking are causing Powell to stay in office. On Wednesday, in an interview on Fox News, Trump blurted out that if Powell doesn’t leave, “I’ll have to fire him,” adding, “I’ve wanted to fire him, but I hate to be controversial.” That’s good to know.

The problem, of course, is that Trump can’t fire Powell. In his daze, he somehow forgot that.

The Supreme Court has not quite ruled definitively on that question in so many words, but in earlier cases on a president’s right to fire other term appointees the Court has indicated that the Federal Reserve is a special category. The Court also blocked Trump’s efforts to fire another Fed governor, Lisa Cook, on fake charges.

And on Tuesday, Trump’s toady prosecutor Jeanine Pirro, U.S. Attorney for the District of Columbia, made another foray to go after Powell on discredited charges that he was negligent in allowing cost overruns in the refurbishing of Fed headquarters. She sent two deputies and an investigator to the Fed construction site. They approached construction workers, but were turned away. Robert K. Hur, a former federal prosecutor hired as outside counsel by the Fed, pointed out that prosecutors were violating federal Judge James Boasberg’s earlier ruling that Pirro’s investigation lacked sufficient evidence to proceed.