Office Depot, which served as the primary sponsor for Tony Stewart's No. 14 car in 22 races this season, announced Sunday it will not return in the same role next season.

The decision leaves a major hole in the sponsor lineup at Stewart-Haas Racing, as Stewart has Mobil 1 for 14 races in 2013 but now needs to find another company to support his racing efforts for the majority of the season.

"The decision to significantly curtail our relationship with Stewart-Haas Racing was very difficult and one that we did not take lightly," said Mindy Kramer, senior director of communications for Office Depot. "However, the changing business landscape warrants a realignment of priorities and resources.

"That being said, Tony Stewart has been an exceptional ambassador for our brand, and he has gone above and beyond in everything that he has done for our company. Being a part of his legendary 2011 championship run was a moment of tremendous pride for everyone at Office Depot."

Team spokesman Mike Arning said SHR is in "continued discussions with Office Depot regarding possible future roles the company could have with the team."

The departure of another major corporation is a blow to NASCAR, and it's even more alarming that the defending series champion wasn't able to keep his sponsor.

SHR had already been looking for funding to keep Ryan Newman in the No. 39 car next year after the U.S. Army announced it was leaving. With Stewart now needing a sponsor (and presumably more of a priority than Newman), it seems even more unlikely everything could come together for a three-car team. Danica Patrick will drive the team's No. 10 car full-time next season with the support of Go Daddy.

Stewart is obviously attractive for sponsors – he's never finished lower than 11th in the point standings and is 14th on the Sprint Cup Series' all time wins list – but September is late in the game to find a big-money sponsor for next season.