Senate Democrats are mounting a final effort to delay the confirmation hearing of Kevin M. Warsh, President Trump's nominee for Federal Reserve chair. In a letter to Senate Banking Committee Chairman Tim Scott, all 11 Democrats argued that Warsh's nomination should be postponed until criminal investigations into current Fed officials Jerome H. Powell and Lisa D. Cook are resolved.

Democrats claim the investigations represent an attempt by the Trump administration to exert control over the central bank. The president has repeatedly criticized the Fed for not lowering interest rates more aggressively. Trump fired Cook last year citing unsubstantiated mortgage fraud allegations, though her term extends until 2038. The Justice Department is also investigating Powell's handling of $2.5 billion in renovations at the Fed's Washington headquarters.

Republicans hold only a narrow 13-to-11 majority on the Banking Committee, meaning Senator Thom Tillis's vow to block any Fed nominee could derail Warsh's confirmation. If Warsh isn't confirmed before Powell's term ends May 15, Powell has stated he will serve as acting chair. Legal experts believe Powell's interpretation is sound, citing Fed delegation authority and recent court decisions requiring Senate confirmation for acting agency heads.