RENO, Nevada - Chris Ault raised Nevada football. After 28 years as coach, he felt he had taken the Wolf Pack as far as he could.

Ault announced late Friday he was stepping down, leaving as the winningest coach in school history, already a Hall of Famer, and having changed the way teams play offense nationwide.

Under Ault, the Wolf Pack went from Division II to I-AA to I-A, winning at every level with some of the most prolific and innovative offenses in the country.

The 66-year-old won 10 conference championships and took the Wolf Pack to the postseason 16 times, including 10 bowl games in 12 FBS seasons. He finished with a record of 233-109-1.

"It's with great humility and mixed emotions I've decided it's time for me to step down and move on," a tearful Ault said at a news conference. "Wolf Pack football firmly established a blueprint for success that can be sustained."

Perhaps his most famous contribution came late in his career, when he invented the Pistol offense in 2005, a scheme now employed by hundreds of teams at every level of football.

The Pistol formation has the quarterback in a short shot-gun formation with a running back lined up directly behind him.

"I'm proud that our offense has broadened the landscape of football. That's exciting," Ault said. "It's here to stay, unlike the wishbone (offense)."

He said he reached the decision to step down after consulting with his wife, Kathy, and Nevada President Marc Johnson. He informed his staff and players of the decision Friday morning.

Ault first broached the subject after Arizona rallied to defeat Nevada, 49-48, in the New Mexico Bowl on Dec. 15. The loss dropped Ault's bowl record to 2-8 and Nevada's season record to 7-6, including losses in five of its final six games.

With most of the Wolf Pack's offensive starters and entire defensive front returning next season, Ault said, the timing was right to turn the program over to a new coach.

"I have focused on leaving the program in the best shape." he said. "I'm sure it'll be a sought-after position."

While he has no plans to return as coach or athletic director at Nevada, he didn't rule out coaching elsewhere. Nevada athletic director Cary Groth is also retiring after this school year.

Ault agreed to a two-year contract extension last February that would have brought his salary to $535,000 by 2015. That's about half the average salary in the Mountain West Conference where he coached this season.

The overall budget of Nevada's football program also is far less than other major football programs, and ranks near the bottom of the Mountain West, Groth said.

Asked whether the limited revenue and loss of coaches were factors in his decision, Ault replied. "All of that plays into the decision ... I want to be a Top 25 program and we have that opportunity, but there are so many intangibles that I had to deal with."

Ault was the only active Division I coach in the College Football Hall of Fame. This season, he passed Bear Bryant for most wins by a coach at his alma mater.

His 40-year career with Nevada began when he played quarterback for the Wolf Pack from 1965-67. He became coach there in 1976 at the age of 29, then the youngest college coach in the nation.

His best season was in 2010 when he led his team to a 13-1 record and a win against Boston College in the Kraft Fight Hunger Bowl. The Wolf Pack, with Colin Kaepernick at quarterback, was ranked No. 13 after upsetting Boise State to win a Western Athletic Conference championship.

Senate Majority Leader Harry Reid, D-Nev., issued a statement hailing Ault as "one of the greatest coaches in college football history."

"Year after year there may have been more highly recruited players in the NCAA, but Coach Ault created a team and taught his players to work together," Reid said. "This philosophy brought the program great success."

Groth, said she never "worked with a finer man" than Ault and would welcome his advice on his successor.

Johnson called Ault's decision "bittersweet." He said he was "really surprised" when Ault told him that he was retiring and he gave him more time to consider the decision.

Ault not only achieved success on the field, but off the field with a high graduation rate for his players and no NCCA problems, Johnson said.

Johnson said he and Groth would work together to find a new coach. A national search firm will be hired to come up with candidates, he said, and the Board of Regents will take final action.

"We want to be competitive, but Nevada isn't in the money game," Johnson said. "We're not a million-dollar-plus place for a coach."