Trump threatens to fire Powell if the Fed chair doesn't leave office on his own

President Donald Trump on Wednesday again threatened to fire Federal Reserve Chair Jerome Powell and said the probe into the renovation of the central bank's headquarters needs to continue.

If Powell stays on as a Fed governor after his successor is confirmed, Trump said he'll have him removed from office.

"Then I'll have to fire him," the president said during an interview on Fox Business. "If he's not leaving on time — I've held back firing him. I've wanted to fire him, but I hate to be controversial. I want to be uncontroversial."

Powell's term as chair expires May 15, and Trump has nominated former Fed Governor Kevin Warsh as his replacement.

Though Powell's time as chair is nearly finished, he has two years remaining on his term as governor. Though most Fed chairs in the past have left the central bank after being replaced, Powell has demurred under repeated questions on what he plans to do.

Powell's exit as chair has been complicated by an investigation into the Fed headquarters renovation. Washington, D.C. U.S. Attorney Jeanine Pirro tried issuing a subpoena to Powell for information regarding the project but was rebuffed by a judge, a decision she is appealing.

At the same time, Sen. Thom Tillis, R-N.C., said he will block Warsh's nomination from leaving the Senate Banking Committee until the probe is finished.

Trump said the investigation must continue.

"What they've done to that so it is probably corrupt, but what it really is is incompetent, and we have to show the incompetence of that," he said.

Last year, Trump tried to replace Governor Lisa Cook following accusations of mortgage improprieties, but has been unsuccessful this far. The case has been argued before the U.S. Supreme Court and is awaiting a decision.

The president also repeated his calls for lower interest rates and said he's confident Warsh will make that happen.