Newman is widely believed to be heading for Stewart-Haas Racing to join Tony Stewart for 2009. Stewart will have 50 percent ownership in what is now Haas CNC Racing next year and is leaving Joe Gibbs Racing to drive there.

"We want to thank Ryan for his hard work and contributions to Penske Racing over the past nine years," said Roger Penske, owner of Penske Racing. "We wish Ryan all the best for the future, and we'll continue to focus our efforts on making the Chase with Ryan and the Alltel Dodge team this season."

Newman won this year's Daytona 500 for his 13th career Sprint Cup victory.

He is 16th in the Cup standings through 19 races. Newman has made all 243 of his career Cup starts in Penske-owned cars, but he has failed to make the Chase in the past two years, finishing 13th and 18th in the standings.

"I appreciate Penske Racing and all they have done for me, but more importantly, I appreciate their friendship and what they have done for my career," said Newman, 30. "I would also like to thank all of the sponsors, especially Alltel, who have supported me."

Penske Racing said a new driver for the No. 12 will be announced "in the near future." Penske test driver David Stremme, who drove in the Cup Series for Chip Ganassi Racing, is considered a leading candidate.