U.S. President George W. Bush on Monday nominated top White House economist Ben Bernanke to succeed Alan Greenspan as Federal Reserve chairman, and the former Fed board governor pledged to keep faith with the Greenspan era, Reuters reported. If confirmed by the U.S. Senate, Bernanke, a widely respected monetary economist with a rich academic resume, would have huge sway over the world's mightiest economy. Greenspan, 79, is set to step down on Jan. 31 after leading the central bank for more than 18 years through a period in which he cemented a reputation as a monetary policy "maestro." "Ben Bernanke is the right man to build on the record Alan Greenspan has established," Bush, flanked by Greenspan and Bernanke, said in a brief Oval Office ceremony.