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President Obama is expected nominate Jack Lew, left, as the Treasury Secretary, replacing Timothy Geithner, right, pictured here during a press conference Sept. 19, 2011 in Washington, D.C.

Updated 12:15 p.m. ET -- President Barack Obama will announce current White House Chief of Staff Jack Lew as his pick to be the next Secretary of the Treasury, CNBC's John Harwood confirmed Wednesday. The announcement could come as early as Thursday.

Lew, who previously served as budget director under Obama and President Bill Clinton, has long been considered the frontrunner to replace departing Secretary Timothy Geithner, the last remaining member of Obama's first-term economic team.

A former investment banker and Capitol Hill aide, Lew was instrumental in crafting the August 2011 debt deal that created the automatic tax increases and spending cuts narrowly avoided in the New Year's "fiscal cliff" agreement.

Those negotiations didn't make Lew a hero to congressional Republicans, who were reportedly irked by his style. Journalist Bob Woodward wrote in his book "The Price of Politics" that top aides to House Speaker John Boehner found Lew "disrespectful and dismissive" and "obnoxious" during the talks.

But, despite the bruising fight set up by the cliff built in the August talks, Lew's strategy ultimately helped set up what observers have deemed a political victory for Obama early in 2013.

A 57-year-old native of New York City, Lew's long familiarity with Capitol Hill began when he took a job as a legislative aide in 1973. He went on to serve for nine years as chief domestic policy adviser to House Speaker Tip O'Neill.

While Lew's announcement is expected soon, per CNBC's Harwood, it's not clear that the president has settled on his new choice for chief of staff.

Deputy National Security Adviser Denis McDonough and former Biden chief of staff Ron Klain are both seen as potential Lew replacements.

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