Donald Trump has formally nominated Kevin Warsh to serve as chair of the Federal Reserve, according to a White House statement. If the Senate confirms the nomination, the former Fed governor would succeed Jerome Powell for a four-year term.

The nomination was sent to the Senate more than a month after the president publicly announced his pick. The confirmation process, however, could face obstacles. Republican Senator Thom Tillis said he would block consideration of the nomination until a federal criminal investigation targeting Jerome Powell is dropped.

That investigation notably focuses on the renovation project at the Federal Reserve's headquarters in Washington, estimated at $2.5bn, as well as Jerome Powell's testimony before the Senate about the project. The Fed chair says the proceedings stem from tensions with Donald Trump over monetary policy. Separately, the Supreme Court has yet to rule in a separate case involving the president's attempt to remove Governor Lisa Cook.