U.S. President Donald Trump said he would dismiss Jerome Powell, chair of the U.S. Federal Reserve, if Powell does not step down after his term ends in May.

Cryptopolitan and other major foreign media reported on April 15 local time that Trump criticised Powell as "incompetent" in an interview. He indicated he could personally dismiss Powell if he does not vacate the post after May, when his term ends. Trump said he considered replacing Powell early in his second term but did not do so to avoid controversy.

The remarks came as an investigation by the U.S. Justice Department’s Office of the Special Investigator (OSI) is under way over a renovation project at the Fed’s headquarters. Trump strongly took issue with the cost of the work, claiming, "A building that would have cost $25 million if I did it is going to end up costing $4 billion." The focus of the probe is said to include a roughly $2.5 billion renovation project involving 2 historic Fed buildings and parts of Powell’s testimony to Congress.

Trump has nominated former Fed governor Kevin Warsh as Powell’s successor, and the Senate confirmation process is under way. The investigation and political sparring are affecting the confirmation process.

Political reactions are mixed. Republican Senator Thom Tillis said he would oppose related nominations, including for the Fed chair, until the Justice Department investigation is concluded fully and transparently. Trump said of Warsh’s confirmation prospects, "We’ll have to check. It might not happen," but added that Tillis would not intentionally block the confirmation.

Legal disputes are also widening. U.S. prosecutors recently visited the Fed headquarters construction site without prior notice but were reportedly told they could not enter without advance approval. Robert Hur, an outside lawyer for the Fed, pushed back, taking issue with the prosecutors’ procedures.

Earlier, U.S. District Judge James Boasberg dismissed 2 related subpoenas, pointing out that the probe could be seen as aimed at pressuring Powell to cut interest rates or resign.

The Senate Banking Committee is due to hold a confirmation hearing for Warsh on April 21. Senate Banking Committee Chairman Tim Scott said the probe would be wrapped up within weeks and the confirmation process would advance, but he did not provide specific grounds.