"At the moment Lance Armstrong hasn't admitted to anything, yet all the evidence is there in this report that he doped," McQuaid said.
Former Armstrong team director Johan Bruyneel is also facing doping charges, but he is challenging the USADA case in arbitration.
On Sunday, Armstrong greeted about 4,300 cyclists at his Livestrong charity's fundraiser bike ride in Texas, telling the crowd he's faced a "very difficult" few weeks.
"I've been better, but I've also been worse," Armstrong, a cancer survivor, told the crowd.
While drug use allegations have followed the 41-year-old Armstrong throughout much of his career, the USADA report seems to have marked a turning point in the saga. Longtime sponsors Nike, Trek Bicycles and Anheuser-Busch dropped Armstrong last week, as did other companies, and he stepped down as chairman of Livestrong, the cancer awareness charity he founded 15 years ago after surviving testicular cancer which spread to his lungs and brain.
Armstrong's astonishing return from life-threatening illness to the summit of cycling offered an inspirational story that transcended the sport. However, his downfall has ended "one of the most sordid chapters in sports history," USADA said in its 200-page report published two weeks ago.
Armstrong has consistently argued that the USADA system was rigged against him, calling the agency's effort a "witch hunt" which pressured witnesses into cooperating.
"It is for Mr. Armstrong to defend himself against such witness statements that he deems to be incorrect. It is not for the UCI to do so," the governing body said in a statement.
If Armstrong's Tour victories are not reassigned there would be a hole in the record books, marking a shift from how organizers treated similar cases in the past.