WASHINGTON (Reuters) - Jack Lew was sworn in as Treasury secretary on Thursday, a White House official said, after winning bipartisan support in the Senate.

Lew, a budget expert and former chief of staff for President Barack Obama, was confirmed by the Senate on Wednesday with 20 Republicans voting for him. He replaces Timothy Geithner, a former regulator with the New York Federal Reserve who left the Treasury last month.

(Reporting by Anna Yukhananov and Mark Felsenthal; Editing by Chizu Nomiyama)