ON BOARD AIR FORCE ONE, Oct 5 (Reuters) - U.S. President Joe Biden retains confidence in Federal Reserve Chair Jerome Powell despite criticism from Senator Elizabeth Warren that the central bank leader failed to regulate the financial system effectively and did not address perceived ethical lapses by top Fed officials. “He does have confidence in ... Powell at this time,” White House spokesperson Karine Jean-Pierre told reporters on Air Force One, referring to Biden. (Reporting by Jarrett Renshaw and Jeff Mason Editing by Chris Reese)