Democratic U.S. Senator Elizabeth Warren on Tuesday called on Federal Reserve Chair Jerome Powell to recuse himself from an internal review of recent bank failures, saying his actions “directly contributed” to them.

The Federal Reserve said on Monday it is reviewing its oversight of Silicon Valley Bank (SIVB.O) in the wake of its abrupt failure Friday.

“Fed Chair Powell’s actions directly contributed to these bank failures. For the Fed’s inquiry to have credibility, Powell must recuse himself from this internal review,” she said in a Twitter post.

A Fed representative did not immediately respond to a request for comment.

Powell said on Monday that the bank’s failure, which set off a wave of concern over the banking system, demanded a “thorough, transparent, and swift review.” Fed Vice Chairman for Supervision Michael Barr would lead the review and the results would be released by May 1, he said.

“It’s appropriate for Vice Chair for Supervision Barr to have the independence necessary to do his job,” said Warren, a Democrat, who has been a sharp critic of Powell.