Obama Picks His No. 2 Security Chief Denis McDonough will be deputy national security adviser By Newser Editors and Wire Services Posted Oct 22, 2010 11:26 AM CDT 8 comments Comments A 2007 file photo of Denis McDonough. (AP Photo/Charles Rex Arbogast, File) (Newser) – President Obama today promoted one of his key national security aides, Denis McDonough, to be his No. 2 national security adviser. He will serve under the new national security adviser, Tom Donilon, who held the second-ranking job himself until recently being promoted earlier this month to succeed Gen. James Jones in the top position. McDonough has been serving as chief of staff to the National Security Council. Previously, he was the council's head of strategic communications under Obama, and he also served a senior adviser to Obama during his presidential run and his transition to the White House.