(CNN) -- Lance Armstrong is ready to cooperate with an international "truth and reconciliation commission" digging into doping in professional cycling, but not -- for now and perhaps longer -- with the U.S. Anti-Doping Agency, which expedited his downfall, his lawyer said Friday.
USADA, designated by Congress as the country's official anti-doping organization for Olympic sports, had reached out to Armstrong's representatives, asking the former champion cyclist to talk to them at length by February 6 about his past.
In a letter dated Friday, Armstrong's lawyer Timothy Herman acknowledged the USADA request but said that "logistically, it is simply not possible" to do in the next two weeks "due to preexisting obligations."
Furthermore, Herman wrote that Armstrong is more inclined to cooperate with international sports authorities -- specifically the Union Cycliste Internationale, which recently announced its intention to set up a "truth and reconciliation commission" in conjunction with the World Anti-Doping Agency.
The lawyer reasoned USADA has limited jurisdiction over the sport, since it has focused on the U.S. Postal Service team once led by Armstrong, but not the vast majority of professional cycling teams that have raced in recent decades.
"USADA has no authority to investigate, prosecute or otherwise involve itself with the other 95% of cycling competitors," Herman said. "Thus, in order to achieve the goal of 'cleaning up cycling,' it must be WADA and the UCI who have overall authority to do so."
U.S. Anti-Doping Agency CEO Travis Tygart, in a statement to CNN, challenged Armstrong's claim he did not have sufficient time to arrange his schedule so he could talk to his organization. Tygart said the two sides met last month, at which time his agency asked Armstrong to work with them and "be part of the solution."
"Mr. Armstrong has already been provided well over a month since our meeting in December to consider whether he is going to be part of our ongoing efforts to clean up the sport of cycling," Tygart said. "Either way, USADA is moving forward with our investigation on behalf of clean athletes."
Last October, the USADA detailed its investigation that found Armstrong played a central role in what it called "the most sophisticated, professionalized and successful doping program that sport has ever seen."
That in-depth report hastened the once iconic Armstrong's demise, including his being stripped of his 2000 Olympic bronze medal and seven Tour de France titles.
As he had for years, Armstrong continued to vehemently deny cheating during his stellar run -- until this month, when he confessed to Oprah Winfrey that he'd used performance-enhancing drugs and had illicit blood transfusions.
In the interview, Armstrong admitted being a "bully" at times, but insisted he didn't feel like he cheated because others in his sport were doing the same.
"I viewed it as a level playing field," the athlete said.
Armstrong told Winfrey he was open to talking with anti-doping agencies, including USADA, to address what he called a pervasive "culture" of breaking the rules to get ahead.
That said, there's a long history of bad blood between the two sides -- including pointed back-and-forth barbs between Armstrong and Tygart.
In his recent interview, Armstrong had admitted some of USADA's findings had merit, but rebutted others, such as its claims he cheated when he returned to professional cycling for the 2009 and 2010 Tour de France competitions.
Tygart said in an interview with CBS' "60 Minutes" set to air in full Sunday that, even if others also took performance-enhancing drugs, Armstrong "was on an entirely different playing field" given how much "inside information" and "special access" he had.
The anti-doping chief blasted Armstrong's claim in his Winfrey interview that he didn't think he was cheating -- saying even a kindergartener could recognize that "it's breaking the rules of the game."
"No real athlete has to look up the definition of cheating," Tygart said, according to excerpts of the interview posted online. "It's offensive to clean athletes who are out there, working hard, to play by the rules that apply to their sport."
Herman expressed "disappointment" about this interview, which he expected would contain "more criticism of and attacks on Lance, despite no shortage of that following his recent revelations."
"Lance's commitment to the truth and reconciliation process is firm, despite the attempt at piling on through more appearances by Mr. Tygart on '60 Minutes,'" the lawyer wrote.
CNN's Kevin Bohn and Joe Sutton contributed to this report.