A practice in the Senate called a “hold” allows a member - through his or her majority or minority leader and without exposing his or her identity - to hold up, virtually indefinitely, a vote on a nomination to the Federal Reserve Board or any other government position that requires confirmation by the Senate.
I have first-hand knowledge of this practice, since a hold delayed the confirmation of my nomination for several months. Actually, the hold was applied to the renomination of the Chairman, but the nominations of myself and Alice Rivlin as governors were viewed as part of a package and therefore action on all the nominations was delayed.