WASHINGTON - Denis McDonough's tenure as White House chief of staff began with a hug, a handshake and high praise from President Obama before an audience of hundreds and a phalanx of TV cameras.

If McDonough does his job well, the public may rarely see or hear from the Stillwater native again.

Making official a move that had been rumored for weeks, Obama appointed McDonough as his chief of staff Friday, making him the first Minnesotan and the president's fifth to serve in the role. He replaces Jack Lew, the nominee for Treasury secretary.

McDonough, 43, graduated with highest honors and played defensive back on the football team at St. John's University in Collegeville before earning his master's degree in foreign service from Georgetown University.

During the announcement, Obama described McDonough as humble and unassuming yet tough, qualities he attributed to McDonough's football career and his upbringing in Stillwater, where he was one of 11 children.

With 10 siblings, "you've got to be tough," Obama said. He added: "I always tease Denis that he made up for modest talents with extraordinary dedication and a high threshold for pain."

McDonough has been a foreign policy adviser to Obama since the president's days in the Senate.

On Friday, Obama credited him with playing a significant role in national security decisions that have defined the presidency, including the end of the war in Iraq, winding down the war in Afghanistan and the repeal of the military's ban on openly gay service members.

In his new position, McDonough will work behind the scenes, guarding access to Obama and seeking support for the president's policies on Capitol Hill and beyond.

He'll also be asked to shift gears, switching his focus from foreign issues to domestic matters, such as immigration, gun control legislation and gay rights.

Presidential scholar and University of Akron political science professor David Cohen said that Obama's ability to achieve his second-term goals will depend largely on McDonough's competence and adjustment to the role.

Current Chicago Mayor Rahm Emanuel, William Daley and Pete Rouse have also served as chiefs of staff under Obama.

"When things are running smoothly in the White House, no one really cares who the chief of staff is," Cohen said. "But if things aren't going well, the person accepts much of the blame."

McDonough spent the early part of his career as a foreign policy aide on Capitol Hill before moving on to legislative director and a stint as a fellow at the Center for American Progress, a liberal Washington-based think tank.

As deputy national security adviser, he was on the ground in Haiti in the aftermath of the earthquake that ravaged the country.

During the Navy SEAL raid that led to the death of Al-Qaida founder Osama bin Laden, McDonough was in the Situation Room, two seats to Obama's left.

Obama also made note of the times that McDonough visited troops in Iraq and Afghanistan and wounded soldiers at Walter Reed National Military Medical Center to learn about the needs of troops.

But McDonough's highest profile job may have come when Obama entrusted him with heading the administration's response to the attack on the U.S. Embassy in Benghazi, Libya, which left four Americans dead.

"Given his humility, I don't think people always appreciate the breadth of his experience and the range of his talents," Obama said. "And it's precisely because of that intellect, that experience, his dedication, his determination, that I wanted Denis in this job."

McDonough, with his wife, three children and three of his 10 siblings in the crowd, deferred to the president, not saying a word during the entire announcement.

"Denis, you're not just one of my closet friends, but you're also one of my closet advisers," Obama told him. "Thank you for signing up for this very, very difficult job."

Corey Mitchell is a correspondent in the Star Tribune Washington Bureau. Twitter: @C_C_Mitchell