Washington (CNN) - President Barack Obama named one of his closest and most trusted advisers as his chief of staff Friday, the fifth man to hold the job since Obama first took office in 2009.
Denis McDonough, who served as Obama's deputy national security adviser since 2010, was announced to the post at a White House event Friday. Obama told a packed East Room that McDonough is a "great friend to me and to everyone who works here in the White House."
"Nobody outworks Denis McDonough," Obama said later - an important trait for the person responsible for a White House staff of hundreds and for controlling access to the president.
Before becoming deputy national security adviser, McDonough served on the national security staff in other capacities. He was also a senior foreign policy adviser for Obama's 2008 presidential campaign. Before that, McDonough worked as a foreign policy adviser for Senate Democratic Leader Tom Daschle.
He's been one of the president's "closest and most trusted advisors for nearly a decade," a White House official said Friday, pointing to McDonough's service in Obama's U.S. Senate office before he ran for president.
Obama has "relied on his intellect and good judgment ever since," the official said.
Originally from Stillwater, Minnesota, McDonough graduated from St. John's University in Collegeville, Minnesota, and has a master's degree from Georgetown University. He's 43, making him one of the youngest White House chiefs of staff in recent decades.
In the immediate aftermath of the 2010 earthquake in Haiti, McDonough acted as the White House's coordinator on the ground, ensuring that U.S. aid was being effectively used in the devastated nation.
He also played a role in the U.S. withdrawal of troops from Iraq, and the drawdown of America's military presence in Afghanistan.
McDonough's role in the 2011 raid on Osama bin Laden's compound in Pakistan was immortalized in a now-famous photo from the White House situation room, which shows him seated next to Secretary of State Hillary Clinton as top Obama aides watched the raid in real time.
McDonough will be Obama's fifth chief of staff since he took office in January 2009. Rahm Emanuel, who went on to become Chicago mayor, was the first to hold the position, followed by Bill Daley, then Jack Lew. Pete Rouse, a former senior adviser and now counselor to the president, served as interim chief of staff for three months between Emanuel and Daley.
Other top White House aides also received promotions at Friday, including communications director Dan Pfeiffer and deputy communications director Jennifer Palmieri. In total, four women were announced in new senior-level positions at the White House Friday, a move that comes as Obama comes under scrutiny for the perceived lack of diversity in his second term Cabinet picks.