Lance Armstrong is giving up his fight against the latest wave of charges by the U.S. Anti-Doping Agency, which will likely rule that the seven-time Tour de France winner is a cheater who should be banned from cycling for life and stripped of his titles.

Armstong, who never tested positive during his career, has denied using performance enhancing drugs. Armstrong, who retired last year, won the sport's ultimate contest from 1999-2005.

“There comes a point in every man's life when he has to say, 'Enough is enough.' For me, that time is now,” Armstrong said in a statement released on his website. "I have been dealing with claims that I cheated and had an unfair advantage in winning my seven Tours since 1999. The toll this has taken on my family and my work for our foundation and on me leads me to where I am today -- finished with this nonsense.”

Armstrong, a survivor of testicular cancer and major fundraiser for research through his Livestrong foundation, had until Thursday night to inform USADA if he would fight the charges, with his last option arbitration. The cycling champion refused that option, saying USADA was ''on a witch hunt" and that the agency didn't have the authority to impose a lifetime ban.

If the agency does impose a lifetime ban and recommend Armstrong be stripped of his titles, the International Cycling Union would have the final say.

Armstrong said his decision is not an admission of guilt.

“USADA cannot assert control of a professional international sport and attempt to strip my seven Tour de France titles,” he said. “I know who won those seven Tours, my teammates know who won those seven Tours, and everyone I competed against knows who won those seven Tours.”

USADA says that Armstrong has used banned substances since 1996, including the blood-booster EPO and steroids.

Armstrong asked for a permanent injunction in federal court against USADA’s charges, saying the agency did not have jurisdiction and that it was violating his constitutional rights to due process. U.S. District Judge Sam Sparks dismissed the case earlier this week. In issuing his decision, Sparks did say USADA’s charging document was of "serious constitutional concern."

Travis Tygart, chief executive of USADA, said the agency has not received confirmation from Armstrong regarding his public announcement and released the following statement:

"It is a sad day for all of us who love sport and our athletic heroes. This is a heartbreaking example of how the win-at-all-costs culture of sport, if left unchecked, will overtake fair, safe and honest competition, but for clean athletes, it is a reassuring reminder that there is hope for future generations to compete on a level playing field without the use of performance enhancing drugs."

Wire reports contributed to this report.

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