CHARLOTTE, N.C. — Joe Gibbs Racing will release Tony Stewart from his contract at the end of the season, ending an incredibly successful decade in which they won two championships and turned the organization into one of NASCAR's best.

Stewart was expected to address JGR employees Wednesday, but his release, which J.D. Gibbs called "bittersweet," was announced by the team.

"While this moment is bittersweet, we're parting on good terms and we know that each of us has benefited greatly from the other," Gibbs said in the statement.

Stewart's departure opens the door for him to buy a NASCAR team. He's had an offer since April to purchase the fledgling Haas-CNC two-car team.

Stewart joined JGR in a developmental role in 1997 while he was still competing in the IndyCar Series championship. He ran five Nationwide Series races for JGR that year, and also won the IRL championship. He expanded his Nationwide schedule in 1998 to 22 events in preparation of his move to full-time NASCAR in the Cup Series.

His arrival helped JGR expand to two teams, and Stewart was an immediate impact on the Cup Series. He set a rookie record with three victories in 1999 while winning rookie of the year, beginning a 10-year run that's seen Stewart win at least two events a season.

With 32 career victories, Cup championships in 2002 and 2005 and more than $68 million in winnings, it's been one of the most steady and successful partnerships in NASCAR history. JGR wanted Stewart to sign an extension to stay with the No. 20 team beyond his current contract, which expires at the end of 2009.

But Stewart instead tested free agency and was tantalized by the idea of owning his own race team.

"While our time together is coming to an end, we know there's still a lot of racing left this season and we plan to make the most of it," Gibbs said. "On behalf of everyone at JGR, we're proud of everything we've accomplished together with Tony and we wish him the best in pursuing his dream of NASCAR team ownership."

Stewart could announce as early as Thursday that he's acquired majority ownership of Haas, which has been run by general manager Joe Custer since owner Gene Haas began serving a two-year prison sentence for tax evasion in January.

He's expected to drive one of the cars, while fellow Indiana native Ryan Newman is believed to be in the running for the second seat. Newman has been noncommittal on his future plans, and the Daytona 500 winner is in the final year of his contract with Penske Racing.

Stewart, who owns several sprint car teams and a trio of race tracks — including famed Eldora Speedway in Ohio — will likely model his NASCAR team after the Gibbs organization. Owner Joe Gibbs has supported Stewart unequivocally through a tumultuous 10 years that saw the temperamental driver punch a photographer, engage in run-ins with fellow drivers, fans and the media, and often fall on NASCAR's bad side through his jaw-dropping candor and sharp wit.

He thanked the organization for sticking by him, and teaching him much of what he knows as a businessman.

"I've learned so much from them and have a tremendous amount of respect for what they've built," Stewart said in a statement. "I've modeled my USAC and World of Outlaws teams the same way they built their NASCAR team, and I made it a point to find good people to run those programs.

"If I've learned anything from my time at Joe Gibbs Racing, it's that Joe Gibbs' saying of, 'You win with people,' is incredibly true. They always surrounded me with not just good people, but great people, and the results speak for themselves."

Stewart's departure means the end of the longest active driver-crew chief relationship in the garage. Greg Zipadelli helped build the No. 20 team around Stewart at inception, and will likely stay behind at JGR to help groom 18-year-old protege Joey Logano into NASCAR's next superstar.

"No matter what, Tony and I will remain close friends," Zipadelli said. "I know when it comes to the No. 20 team, things will obviously be a lot different next year, but I remain as committed as ever this year to winning races with Tony and securing our spot in the Chase to contend for a third championship."

Although Gibbs officials have not said who will replace Stewart in the No. 20, Logano is expected to fill the seat. They had quietly shopped the ride to the top free agents in NASCAR, but Carl Edwards passed on the job in May and JGR officials are now confident Logano is up for the challenge.

He made his NASCAR debut in the Nationwide Series in June at Dover following his 18th birthday and finished sixth. He won the pole in Nashville the next week, and became the youngest winner in series history with a victory at Kentucky in just his third start.

Through four starts, Logano has a first, second and sixth-place finish. He's expected to grab Home Depot, which has sponsored Stewart the past 10 years, to keep much of the No. 20 team intact.

Joe Gibbs said the future of that team is bright, even without Stewart.

"The 20 car has been one of the all-time great partnerships in NASCAR for the last decade with the combination of Tony, Zippy, The Home Depot and Joe Gibbs Racing," Joe Gibbs said. "While we are losing one piece of the puzzle, we think the No. 20 team will remain strong for many years to come."