LINCOLN, Neb. -- As Nebraska's coach, Tom Osborne had one of the most successful runs in college football history.

As athletic director, he pulled the football program he and Bob Devaney built out of a nosedive and repaired a fractured department where staff morale had nearly bottomed out.

And now, he's almost done.

The 75-year-old Osborne announced Wednesday that he will retire Jan. 1 after five years on the job. He'll become athletic director emeritus and stay involved in department operations through July 30.

"At some point, whether you're able to function or not, just the perception that you're getting old can get in the way," Osborne said. "I don't want to be one of those guys everybody is walking around wringing their hands trying to figure out, 'What are we going to do with him?' That happens sometimes."

Osborne, who had double-bypass heart surgery in 1985, said he has no health issues that led to his decision.

"I'm probably healthier today than when I was a member of Congress," he said. "That takes a big toll on you."

Osborne's first acts as AD were to fire Bill Callahan as football coach and hire Bo Pelini, who has returned the proud program to its winning ways. He shepherded the school's move from the Big 12 to the Big Ten and initiated building projects including a 16,000-seat downtown basketball arena that opens in 2013, a Memorial Stadium expansion that increases capacity to more than 90,000 and the Hendricks Training Center for basketball and Olympic sports.

This past August, Osborne told chancellor Harvey Perlman that he thought he had done about all he could do to position for the future what traditionally has been one of the nation's most competitive athletic programs.

Perlman agreed, saying the university and the state of Nebraska "are in his debt."

Taking over the 23-sport department was a massive undertaking, and one Osborne wasn't sure he wanted. But the native Nebraskan said he felt a sense of duty when Perlman asked him in 2007 to take over for Steve Pederson, who had been fired a few days earlier.

At the time, Callahan's football team was on its way to a 5-7 season including some of the most embarrassing losses in program history. Former football players spoke publicly about feeling frozen out by Callahan and Pederson. There was a disconnection between donors and the department.

"The first day that I was on the job, it was 8 o'clock in the morning and I walked into a meeting with the executive team and we had maybe two or three mental-health counselors who were talking to them about stress reduction," Osborne said. "I thought, 'This is odd.'

"I wouldn't say things were awful, but things were a little fragmented and some people quit and some were thinking about quitting. So it was kind of a difficult time, but people pulled together very quickly."

Dale Jensen, a major athletic donor, said Osborne was exactly the man Nebraska needed at the time.

"Pederson tried to do everything he could to reinvent the program to his own liking," Jensen said. "It had its own life. You can't reinvent the program. Quite frankly, I can't think of one other person who could have stepped in with the credibility Tom had to right the ship."

Perlman called the circumstances around Nebraska athletics "unfortunate" before Osborne took over.

"There was considerable anxiety among the fans and supporters of Husker athletics," Perlman said. "I think the last five years have demonstrated Tom's ability to bring those constituents together."

Perlman said Jed Hughes, a consultant from the Korn/Ferry International search firm, has been hired to identify candidates to succeed Osborne. Perlman said he has already conducted some interviews.

Perlman said he would keep details of the search and identities of candidates private. He said he hoped to make a hire "reasonably soon."

"I think Nebraska is an important enough place in intercollegiate athletics that we should be able to attract the very best to this position," Perlman said. "I can tell you that individuals who currently hold high positions in intercollegiate athletics will not participate in a public search."

Besides the success his Cornhuskers football teams enjoyed from 1973-1997, Osborne served in Congress and lost a gubernatorial bid before returning to the university in 2007. In addition to hiring Pelini, who led the Huskers to the Big 12 championship game in 2009 and 2010, Osborne brought in Tim Miles from Colorado State to coach men's basketball and former major-leaguer Darin Erstad to coach baseball at his alma mater.

Though Osborne fired him, Callahan told The Associated Press he was happy for his former boss and wished him well.

"The old coach did retire. He's paid his dues," Callahan said. "He's got such a great love for Nebraska that I thought he was going to probably be there forever... I think he's a smart man, one of the greatest football, college football, coaches in the history of the game."

Each of the 25 Nebraska football teams Osborne coached won at least nine games, and three of his last four teams won national championships. He left coaching after the 1997 season with a career record of 255-49-3, an .836 winning percentage that ranked fifth all-time among Division I coaches, and 13 conference titles.

He was inducted into the College Football Hall of Fame in 1998.

Osborne turned to politics after his coaching days. By overwhelming margins, voters in the western Nebraska district elected him to the House of Representatives in 2000, 2002 and 2004. In perhaps the greatest upset in Nebraska political history, Osborne lost to incumbent Dave Heineman in the 2006 Republican gubernatorial primary.

Osborne finished his third term after the crushing defeat, then returned to the university to teach classes in leadership and business ethics before he took over the reins of the athletic department.

"I feel we're well positioned," Osborne said. "We worked hard on the culture and part of that has not just been internal. We've tried to link this place with the former players. ... Whatever we've accomplished couldn't happen if we didn't have a united fan base. It would be hard to find one equal to our fans around the country. It allows a program in a state of 1.8 million to be competitive with programs in densely populated areas."