Update: At 6 a.m. ET. Jan. 10, White House Announcement:
The White House has officially confirmed that President Obama will nominate his chief of staff, Jacob "Jack" Lew, to be the next Treasury secretary. According to a statement, the announcement is scheduled for 1:30 p.m. ET today (Thursday).
Ask the average person — even in Washington — who serves as President Obama's chief of staff and you'll probably get a blank stare.
Jack Lew hasn't been heard or seen in the "fiscal cliff" drama unfolding between the White House and Congress. But the former budget director, who took over the top White House job last January, has become a key player behind the scenes.