WASHINGTON - As an all-conference defensive back at Stillwater High School, Denis McDonough was never the fastest or most physically imposing player on the football field, his former coach recalls.

But he was always the smartest, said George Thole of Stillwater.

"He had a good comprehension of what was [happening] on the field," Thole said. "You could always count on him to make the right decision."

Friends and acquaintances say it's no surprise that the instincts and dedication McDonough displayed on the field have propelled the 43-year-old Minnesota native to the cusp of one of the most powerful positions in the U.S. government: White House chief of staff.

Though the decision is not yet official, President Obama is expected to name McDonough to the post within days. McDonough would be the fifth person to serve Obama in that role.

He will take the job as Obama embarks on a second term that is expected to be every bit as contentious as the first, with battles looming over the debt ceiling, spending cuts, gun control and potential changes to the tax code.

Presidential scholar and University of Akron political science Prof. David Cohen has interviewed more than a half-dozen former chiefs of staff for a book he's writing on the post. Cohen calls the chief of staff the "most important unelected position in government," one that requires an unquestionably loyal confidant, savvy decision-maker and dogged defender of the president.

"They must see the whole field for the president," Cohen said. "Everything goes through them. They're often the first staffer the president sees in the morning and the last person the president sees before making a decision."

McDonough has drawn some criticism for the role he has played as a gatekeeper for the president, particularly regarding Afghanistan and Syria, where he has been perceived as screening out advocates who wanted Obama to consider different approaches to the wars raging in those countries.

But he also receives strong praise from people familiar with his White House work.

Former Obama deputy press secretary Bill Burton, a University of Minnesota graduate, said McDonough's experience on Capitol Hill and in the West Wing have prepared him well. The two began working together in the early days of Obama's first presidential campaign.

"Denis understands how to get a job done," Burton said.

Minnesota roots

McDonough graduated with highest honors from St. John's University in Collegeville before earning a master's degree in foreign service from Georgetown University in Washington.

Professors at St. John's remember him as a brilliant, diligent student. College buddies and former co-workers praise his tenacity, humanity and understated humor.

The product of a large Catholic family, McDonough was the third-youngest of 11 children. When he was a child, his brothers and sisters called him "Dude," a nickname that has stuck with him through adulthood and one that the president has been said to use, too.

He has traveled the globe as a trusted foreign policy adviser to the president, but his alma mater and home state are never far from his mind.

When McDonough's college football coach, John Gagliardi, announced his retirement in the fall, a commendation from the White House praised his six-decade career. McDonough also carves out time each year for students at the College of St. Benedict and St. John's Washington, D.C., summer study program.

A college friend and current St. John's professor, Matt Lindstrom, runs the program. One of the annual highlights is a McDonough-led tour of the White House, including a visit to the fabled Situation Room. It's the room where McDonough sat two seats to Obama's left as the president and top-ranking aides watched the Navy SEAL raid that led to the death of Al-Qaida founder Osama bin Laden.

"Not much has changed about Denis [since college] except his portfolio of experience," Lindstrom said. "He's a level-headed, humble, Minnesota-roots guy."

A few years back, McDonough mailed his old high school football coach an appreciation letter on White House stationery. Thole says it was addressed simply to George Thole, Stillwater, MN. No address, no ZIP code.

"That kind of impressed me," Thole said. "But I'm not the least bit surprised. ... Looking back on it, of all the players I've coached, if I had to pick one who was going to be in the White House, I'd have to start with 'Dude.'"

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