Tony Stewart, right, and Joe Custer, general manager of Haas-CNC Racing, attend a news conference Thursday at which they announced that Stewart will become a driver for and co-owner of the NASCAR team next season.

JOLIET, Ill. — Tony Stewart knows he's taking a gamble by leaving NASCAR's elite Joe Gibbs Racing team to join one that usually runs in the middle of the pack.

But Stewart also can imagine what it might feel like to be in victory lane at the Daytona 500 both as a driver and a car owner, so it's a risk he's willing to take.

Having recently negotiated a release from his Gibbs contract at the end of this season, the two-time Cup series champion announced Thursday that he will join the team currently known as Haas-CNC as an owner-driver in 2009.

"There's no guarantees that this is going to be successful," Stewart said. "But after sitting down and evaluating what the potential of this team is, I wouldn't have made this decision if I didn't think it would be successful and if I didn't think it had the potential to be great."

Stewart will be given a 50 percent ownership stake in the team, which will be renamed Stewart-Haas Racing. The two-car team currently fields the No. 66 car for Scott Riggs and the No. 70 car for Jason Leffler, and both cars are outside the top 35 in owners points going into Saturday's race at Chicagoland Speedway.

The move had been widely anticipated, but Stewart confirmed it to his current crew members and other Gibbs employees at the team's race shop Wednesday.

"I wondered how it was going to feel," Stewart said. "I wondered how everybody was going to react."

But Stewart said after he spoke, several employees stood in line to congratulate him.

"We could never be mad or hold that against him," said Stewart's longtime crew chief, Greg Zipadelli. "His success, our success as a group, would not be possible without him."

A plan to stay involved in NASCAR after he's done driving is important to Stewart, who already has several financial interests in racing — including ownership of Sprint Car teams and grassroots race tracks.

Stewart and Haas-CNC general manager Joe Custer did not directly confirm the financial details of Stewart's ownership stake in the team. But both Custer and Stewart strongly hinted that adding Stewart's name and fame to the marquee was enough, and he wouldn't be investing a large chunk of his own money.

Is that really enough to warrant giving him half the team?

"He doesn't just put his name on it. He puts his heart into it," Custer said. "What's Tony Stewart's heart worth?"