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Jack Lew, President Obama's nominee to replace outgoing Treasury Secretary Tim Geithner, is no stranger to Washington politics.

Lew, 57, currently serves as Obama's chief of staff - a position he's held since January 2012.

Lew has kept a low profile in that role and is likely unfamiliar to those outside the beltway, though he has decades of experience.

A graduate of Harvard University and Georgetown Law School, Lew has served as director of the Office of Management and Budget under two Democratic presidents - Barack Obama and Bill Clinton. He served as OMB director from 1998 to 2001 and, as ABC's Jonathan Karl reported, he helped to craft a budget agreement that led to a budget surplus - a factor in Obama's decision to place Lew at Treasury ahead of the impending congressional debate over raising the country's debt-ceiling.

Lew has also worked in the private sector. From 2006 to 2008, he served as the chief operating officer of the Alternative Investment Unit at Citigroup. He is an orthodox Jew who observes the Sabbath and, therefore, does not work from sundown on Friday until sundown on Saturday.

Despite his years working in top jobs in Washington, he's not a full-time resident. He commutes home to the Riverdale section of the Bronx in New York on the weekends.

Lew's already begun to gain some attention since news of the president's plan to nominate him first broke, but for reasons that are not related to his experience. His signature - which, if he is confirmed as Secretary of the Treasury, would appear the nation's $1 bills - has been the subject some internet discussion. It's very messy- so much so that on Wednesday it prompted a reporter to ask White House press secretary Jay Carney if Lew was working on the signature.

"Not that I'm aware of," Carney said.