With the appointment of Jack Lew as White House chief of staff, President Obama today rivaled his modern day predecessors for the number of shake-ups in that post during in a single term.

Since January 2009, four close Obama aides have held the key administration position, which oversees the executive cabinet, outnumbering what many presidents have had in eight years.

Rahm Emanuel served as chief of staff through October 2010 before leaving to run for mayor of Chicago, an office he now holds. Pete Rouse then took over as acting chief of staff for three months until Bill Daley was appointed on Jan. 6, 2011.

Presidents Bill Clinton and Ronald Reagan each had four chiefs of staff total over the course of their two terms, while George W. Bush had just two chiefs of staff spanning a similar eight-year period.

George H.W. Bush had three chiefs of staff in his single term. Gerald Ford, Jimmy Carter and Richard Nixon each had two.

"I think it makes sense to see this as Obama's third chief of staff, since Rouse only had the job on an interim basis because Emanuel resigned so quickly to pursue elected office," said U.S. Naval Academy professor and presidential historian Brendan Doherty.

"The parallel that comes to mind is George H.W. Bush, who had three chiefs of staff over his four years in office. One key difference is that Obama's first chief of staff left of his own volition… while John Sununu [Bush's first chief of staff] left after the uproar over his use of government planes for personal purposes," he said.

Doherty noted that Bush's second chief of staff also departed abruptly in an election year, a move interpreted at the time as an effort to coordinate operations of the White House with the campaign.

"Obama already has other advisers, most prominently David Plouffe, to do that," he said, drawing the contrast.

Lew, 56, has until today been director of the Office of Management and Budget, a cabinet-level role he assumed in November 2010.

He is a veteran of Democratic administrations, serving as OMB director in the Clinton White House from 1998 to 2001, and spending nearly two years as deputy Secretary of State for management and resources under Hillary Clinton.

Prior to joining the Obama administration, Lew was a hedge fund manager for Citigroup.

During the 1970s and 1980s, Lew worked on Capitol Hill first as a legislative aide and later policy adviser, political experience that could prove useful in his new role during the months ahead.

"Ever since he began his career in public as a top aide to Speaker Tip O'Neill, Jack has fought for an America where hard work and responsibility pay off, a place where everybody gets a fair shot, everybody does their fair share, and everybody plays by the same rules," Obama said today. "And that belief is reflected in every decision that Jack makes."