US President Donald Trump has threatened to fire Federal Reserve Chair Jerome Powell if he does not step aside at the end of his term in May.

The two have been embroiled in a bitter spat over Powell's reluctance to cut the central bank's interest rate, despite Trump's repeated calls.

Powell's term expires on 15 May, but he is planning to remain in post until his successor, Kevin Warsh, is confirmed by the Senate.

"Then I'll have to fire him," Trump told Fox Business, when asked about Powell's plans to stay on in the job.

"I've held back firing him. I've wanted to fire him, but I hate to be controversial," Trump said.

Thom Tillis, an influential Republican senator on the committee which oversees nominations for the Federal Reserve chair, has threatened to block Warsh's confirmation.

If Warsh is not confirmed before Powell's term expires, he plans to stay on temporarily in the post.

"That's what the law calls for. That's what we've done on several occasions," Powell has said.

Tillis has warned Trump he will not let Warsh's appointment go ahead unless a criminal investigation into Powell, linked to the renovation of the Federal Reserve building, is dropped.

Trump said he was hopeful Tillis would drop his opposition to the appointment, adding that he "is an American… he knows what to do".

But he said he was not prepared to have the probe into Powell dropped.

He told Fox Business: "Don't you think we have to find out what happened there? I have to find out."

Trump has accused Powell of mishandling the Federal Reserve renovation, spending billions of dollars on a project which he suggested could have been carried out for tens of millions.

He has previously branded Powell a "knucklehead" and claimed he was "doing a lousy job" after his repeated calls for interest rate cuts were ignored.

Stock markets and the US dollar slipped after it emerged in 2025 Trump had broached the idea of firing Powell.

The US president quickly denied he was going to sack him, adding: "It's highly unlikely unless he has to leave for fraud."

If Trump were to fire Powell, it would be a major break with precedent and mark the first time a Federal Reserve chair has been fired.

Trump appointed Powell to lead the Federal Reserve during his first term in 2017, praising his "steady leadership, sound judgement, and policy expertise". He was reappointed by Joe Biden in 2021.