President Donald Trump said he will fire Federal Reserve Chair Jerome Powell if he does not step aside when his term expires next month.

“Then I’ll have to fire him,” Trump told Fox Business’ Maria Bartiromo Wednesday in response to a question about Powell staying on at the Fed.

Powell’s tenure as chair expires on May 15. Trump’s pick for a replacement, Kevin Warsh, has yet to be confirmed by the Senate and the full chamber. That leaves the potential for Powell to remain in place as chair “pro tempore,” per Fed regulations.

Powell confirmed at a press briefing in March that if Warsh isn’t confirmed by the Senate by May 15, Powell would remain as Fed chair “pro tem” in the interim. “That’s what the law calls for. That’s what we’ve done on several occasions,” Powell said at the time.

The Senate Banking Committee has scheduled a confirmation hearing for Warsh for April 21. However, North Carolina Republican Sen. Thom Tillis, a key member of the committee that votes on central bank nominees, has said he will not vote to confirm Warsh until a Department of Justice criminal investigation into Powell has concluded.

Trump has repeatedly criticized Powell for not lowering rates to the president’s liking and his administration has zeroed in on the Fed’s $2.5 billion-dollar renovation of its Washington, DC, headquarters, as a possible pathway to oust the central bank head.

Trump on Wednesday said he was hopeful that the Senate Banking Committee would confirm Warsh next week, saying Tillis “is an American; he knows what to do.”

But he also acknowledged Tillis may stick to his guns and that the probe, led by US Attorney for the District of Columbia Jeanine Pirro, could interfere with his ability to get Warsh seated at the Fed next month.

Trump said he wanted Powell out at the Fed – but not enough to ask Pirro to call off the investigation.

“Does that mean we stop a probe of a building that I would have done for $25 million that’s going to cost maybe $4 billion? Don’t you think we have to find out what happened there?” Trump said in the interview conducted at the White House. “I have to find out.”

The president called Powell a “disaster” for the country.

“Here’s a man who took this little, tiny building and a couple of other little, tiny complex, and he’s spending more than $3 billion. I want to know who the contractor is, because that contractor is making billions of dollars, perhaps.”

“It is probably corrupt, but what it really is is incompetent, and we have to show the incompetence of that,” Trump said.

The Fed has said the cost overruns are due to “unforeseen conditions” requiring more spending to rectify, such as “more asbestos than anticipated, toxic contamination in soil, and a higher-than-expected water table.”

Trump said if he’s forced to fire Powell – a legally dubious action – so be it.

“I’ve held back firing him. I’ve wanted to fire him, but I hate to be controversial,” Trump told Bartiromo.

Powell said last month he would not step down from the Fed as long as the Department of Justice’s criminal investigation is ongoing.

“I have no intention of leaving the Board until the investigation is well and truly over with transparency and finality,” Powell said.

Powell’s tenure as Fed chair ends May 15 and his term as governor ends in January 2028. He said he has not made a decision about whether he would continue to serve on the Board.