KANSAS CITY, Mo. — Kansas City Chiefs president and general manager Carl Peterson has resigned, effective at the end of the season.

Owner Clark Hunt confirmed the resignation today.

Peterson took over in 1989. He hired Marty Schottenheimer as coach and they built the Chiefs into an NFL powerhouse over the next 10 years.

However, Kansas City faltered the past decade and seemed to hit a low point with an emotionally draining 22-21 loss Sunday to San Diego, which left the Chiefs 2-12.

"On behalf of my family and the entire Kansas City Chiefs organization, I want to thank Carl for his two decades of service to the Chiefs," team owner and chairman Clark Hunt said in a written statement. "Both Carl and I agreed that immediately initiating the search for the next Chiefs general manager would be the best thing for the future of the organization, and he will be resigning following the 2008 season."

During Peterson's 20 years at the helm, the Chiefs amassed a 176-141-1 record, won the AFC West four times and reached the AFC Championship game in 1993.

"I am proud of my association with the Kansas City Chiefs and our many accomplishments over the last 20 years," Peterson said in a statement released by the Chiefs. "I thank the Hunt family for the opportunity to lead the Chiefs organization and sincerely appreciate all the coaches, players, administrators and Chiefs employees with whom I've had the pleasure of working in my time here. Most importantly, I want to thank Chiefs fans around the country for their passionate support through the years. Chiefs fans are the finest in all of professional football."

Vice president Denny Thum will serve as interim president and general manager.

Hunt said he would speak with reporters later in the day.