The news came from team spokesman Mike Arning on Sunday, shortly before the defending Sprint Cup champion started from the pole in the NASCAR race at Atlanta Motor Speedway.
Mobil 1 is set to return as a primary backer for about half the races next year, but Stewart will have to find someone to pick up the rest of the tab for his No. 14 car. The three-time Cup champion also is searching for sponsorship on Stewart-Haas Racing's second car, the No. 39 machine driven by Ryan Newman. The U.S. Army is dropping out.
Office Depot praised Stewart but says it's leaving NASCAR because of "the changing business landscape."