(CBS/AP)-- President Obama is set to formally announce this afternoon that longtime national security adviser Denis McDonough will become his next chief of staff. The president will make the announcement at 12:10 p.m. today in the East Room of the White House.
McDonough will replace Jack Lew who has been nominated to replace Timothy Geithner as Treasury Secretary. The 43-year-old McDonough most recently served on the president's national security team and played an instrumental role in winding down the wars in Iraq and Afghanistan and the nuclear crisis in Fukushima, Japan. He was also among the national security team in the same room as the president during the raid that killed Osama bin Laden.
"Denis has been one of the President's closest and most trusted advisors for nearly a decade, dating back to when he helped set up then Senator's Barack Obama's Senator office," a White House official said in a statement. "He has relied on his intellect and good judgment ever since."
McDonough will be the president's fifth chief of staff, following Rahm Emanuel, William Daley, Pete Rouse, who briefly served as interim chief of staff, and Lew.
While his experience is in national security and foreign policy, he has little experience dealing with the lobbying community or big party donors, CBS News Chief White House Correspondent Major Garrett has pointed out.
McDonough is one of several staff changes at the White House to be announced today. Rob Nabors, the director of legislative affairs who negotiated with Republicans in Congress on the "fiscal cliff", will now become deputy White House chief of staff for policy. Assistant Attorney General Lisa Monaco has been elevated to deputy national security adviser and communications director Dan Pfieffer will replace David Plouffe as one of the president's closest aides as assistant to the president and senior adviser.