Discovery Channel will cease operations at the end of this season because of its struggle to find a new sponsor. Doping scandals have left cycling reeling in crisis and made sponsors jittery.

"I do not think you have seen the last of this organization in the sport," Armstrong, the retired cycling great and a co-owner of the team, said in a statement Friday. "But clearly things need to improve on many levels, with a more unified front, before you would see us venture back into cycling."

Discovery Channel featured the winner (Alberto Contador of Spain) and third-place finisher (Levi Leipheimer of the U.S.) at last month's Tour de France.

On Friday, Contador denied any involvement in doping following accusations he was linked to the Operation Puerto drug investigation.

"This was a difficult decision, not made any easier by our recent Tour de France success," general manager Bill Stapleton said. "We were in talks with a number of companies about the opportunity and were confident a new sponsor was imminent. We have chosen, however, to end those discussions."

The team said it will still ride in this year's Tour of Spain and the Tour of Missouri.

Tailwind Sports, which owns and operates Discovery Channel, suggested in its statement that Armstrong's mentor, Johan Bruyneel, will retire. He coached Armstrong through his record seven Tour de France wins and Contador through his title, meaning he oversaw victories in eight of the last nine Tours.

"When I came to direct this team in 1999 I never would have imagined that we could achieve this level of success. It was an amazing time in my life and the lives of all the staff and riders associated with this team," Bruyneel said.