Obama names Denis McDonough as chief of staff

President Obama formally announced this afternoon that longtime national security adviser Denis McDonough will be his next chief of staff.

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.

"He's been one of my closest and most trusted advisers," the president said at a news conference in the East Room of the White House, adding that he's "not just one of my closest friends [but also] one of my closest advisers."

McDonough has worked for the president since his the newly-elected Senator first came to Washington. After the electoral loss of his previous boss, Senate Majority Leader Tom Daschle, D-S.D., McDonough helped Mr. Obama set up his Senate office. He went on to be a foreign policy adviser during his 2008 campaign and joined the White House staff after the president's election.

The president called him "indispensible" and someone who "understands the importance of reaching across the aisle."

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 announced today. David Plouffe's last day at the White House is today. He was Mr. Obama's 2008 campaign manager and has played a key role in policy and politics since. Dan Pfieffer will be promoted from communications director to Plouffe's role as assistant to the president and senior adviser.

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.