“I think it’s very valuable to them to know exactly how Lance avoided getting caught and how tests were evaded,” said Jonathan Vaughters, a former Armstrong teammate, a vocal antidoping proponent and a current co-owner of the Garmin-Sharp professional cycling team. “They need someone on the inside to tell them how it was done, and not just anyone on the inside, someone on the inside who was very influential. Someone like Lance.”

Vaughters said that a confession by Armstrong might encourage other riders to say what they knew and encourage a “truth and reconciliation” effort, in which riders would not be penalized for confessing to doping if they detailed how they got away with it. That effort could educate authorities so those entities could bolster drug testing and close any loopholes, Vaughters said.

“I feel like Lance’s confession could push that effort forward dramatically,” he said. “Right now, we almost have to destroy the sport in order to save it.”

The antidoping agency has already brought cases against five of Armstrong’s former colleagues. Michele Ferrari, an Italian doctor and Armstrong’s trainer, and Luis García del Moral, a team doctor, have accepted lifetime bans. The three others who had worked on Armstrong’s teams have requested that their cases go to arbitration: Johan Bruyneel, the team manager, who remains a powerful influence in the sport; Pepe Martí, a team trainer; and Pedro Celaya, a team doctor.

If Armstrong gives an admission to the antidoping agency, his testimony might help the agency win those cases. It also might help the agency find out who, if anyone, in the hierarchy of cycling was involved in the cover-up.

At least two of Armstrong’s former teammates have claimed that the International Cycling Union, cycling’s worldwide governing body, made the results of a failed drug test at the 2001 Tour of Switzerland disappear for Armstrong. Only Armstrong might be able to say if that is true.

David Howman, the director general of the World Anti-Doping Agency, said he hoped to have the opportunity to speak with Armstrong about any doping that Armstrong may have done. He might have the opportunity to do that sooner than he thinks.