Powell's second term as Fed chair ended Friday, and Warsh has been confirmed by the Senate. Until the swearing-in happens, Powell is still running the building.
The Federal Reserve Board voted on Friday to name Powell chair pro tempore, which is Latin for "for the time being."
The board called the move "consistent with past practice during similar transitions between chairs," and it kicked off the morning after Powell's second four-year term as chair officially expired.
The vote was 5-1, with Governor Stephen Miran voting no and Vice Chair for Supervision Michelle Bowman abstaining.
The two said in a joint statement that the temporary designation should have a clear end date or be subject to renewal by another vote or by presidential action.
Warsh was confirmed by the Senate 54-45 to be the Fed's 17th chair, and the White House has not yet announced when he will be sworn in.
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Powell is not leaving the Federal Reserve when Warsh takes over.
His seat on the Board of Governors runs through 2028, and he has said he plans to keep it.
Powell has tied that decision to the Trump administration's criminal investigation of him, saying he will give up the governor's seat only once he is fully satisfied the probe has been dropped.
Warsh will take the seat that Miran is leaving, after Miran submitted his resignation as governor on Thursday, effective the moment Warsh is sworn in.
The Fed has never run a transition quite like this, with the outgoing chair staying on the board and the incoming chair confirmed but not yet seated.
Two of the governors voted against the way leadership is being handled in between, which signals real friction inside the building.
For markets, the next move that matters is whether Warsh signals a different rate path on day one.
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