MILAN -- Cycling's governing body says it could respond "at any time" to allegations by the U.S. Anti-Doping Agency that seven-time Tour de France winner Lance Armstrong was a serial drug cheat.

The International Cycling Union received the USADA's report last week and has until Oct. 31 to determine whether to appeal the anti-doping agency's decision to strip Armstrong of his Tour titles.

UCI spokesman Enrico Carpani told The Associated Press on Thursday that its decision on a possible appeal to the Court of Arbitration for Sport

"could happen as early as tomorrow."

He added: "From now on be very careful, because the UCI decision could be any time."

The news comes one day after Nike dropped its sponsorship deal with Armstrong, and after the cyclist himself revealed he would step down as chairman of Livestrong, his charity organization.

On Thursday, Livestrong CEO Doug Ulman appealed to its members with a letter on the charity's website that said: "Please make a donation today to support LIVESTRONG's programs for cancer survivors. Send a clear message that we will NEVER YIELD in our commitment to stand with them."

Oakley, one of the few companies that didn't dump Armstrong on Wednesday, issued a new statement Thursday referencing the mounting evidence against the cyclist, as well as its position to be one of the last to jump ship.

"As guilty as the evidence shows, which we completely acknowledge, it is our promise and contractual obligation to stand by our athletes until proven guilty by the highest governing body of sport, or a court of law," Oakley said in a statement, which was also posted on the company's Twitter account. "We might be last off, but we are not going to jump on the bandwagon as it breaks our promise to all of our athletes. We will wait for the UCI's conclusion and act at that time."

Oakley remains Armstrong's lone personal endorsement after bike parts maker SRAM parted ways with Armstrong on Thursday.

"SRAM is officially terminating its product sponsorship agreement with Mr. Armstrong," the company said in a statement provided to ESPN. "SRAM is disappointed with the revelations that the USADA report has brought forth. Moving forward, SRAM will maintain its support of the Livestrong Foundation, as we believe in its purpose and value."

Armstrong had a small share of a minority private equity investment in SRAM beginning in September 2008, but SRAM bought out that private equity investment in June 2011.

Former UCI president Hein Verbruggen told The Associated Press in a telephone interview Thursday he would not comment on the detailed USADA allegations before the UCI issues a reaction.

"The UCI is studying the USADA report and they will issue a report ... toward the end of next week," said Verbruggen, who was UCI president from 1991 to 2005.

Armstrong won the Tour de France seven straight times from 1999 to 2005.

Spain's anti-doping agency (AEA) said state prosecutors could seek retroactive punishment against those who may have broken national laws during their alleged involvement in the Armstrong doping scandal.

The AEA says it handed USADA's dossier over to prosecutors to investigate whether charges should be invoked for crimes committed in Spain.

Spanish doctors Luis Garcia del Moral, Pedro Celaya and Pepe Marti are alleged to have been key figures in what USADA calls "the most sophisticated doping program that sport has ever seen."

Former team principal Johan Bruyneel, Armstrong's former manager, was a Spanish resident at the time.

USADA banned Armstrong for life and said he should be stripped of his Tour titles because of his involvement in "the most sophisticated, professionalized and successful doping program that sport has ever seen."

Verbruggen issued a statement through the UCI on Thursday contesting an article in Dutch newspaper De Telegraaf that said he believed there is no evidence against Armstrong.

"My reaction (to the newspaper) was strictly limited to the fact that Lance Armstrong was never found positive by the anti-doping laboratories, that there was no positive test and that there was nothing to be covered up," Verbruggen said.

The USADA evidence cites several of Armstrong's former teammates who detail entrenched doping among riders on Armstrong's teams during his Tour wins.

Nike issued a statement explaining it dropped the sponsorship of the rider "due to the seemingly insurmountable evidence that Lance Armstrong participated in doping and misled Nike for more than a decade."

Information from ESPN.com sports business reporter Darren Rovell and The Associated Press contributed to this report.