Lance Armstrong has voiced his objection to David Millar's candidacy for presidency of the CPA, saying his former teammate is "the last person that would come to mind" to lead the union of professional cyclists.
Armstrong, who is banned for life from sport following his confession to doping during his seven Tour de France victories, was a teammate of Millar at Cofidis in 1997 during the Briton's first season as a professional.
Millar, who has primarily been working in television commentary since his retirement in 2014, recently announced his desire to become CPA president, challenging the incumbent Gianni Bugno on a manifesto of transforming the organization into one truly representative of riders' interests.
"Millar is probably the last person that would come to mind for this role," Armstrong told the Guardian on Wednesday.
"I wouldn't even call it change because there's nothing really there to even consider changing. I'd propose creating a real union for the riders, not the window dressing that is the CPA."
Millar has led a vocal campaign on social media and replied to Armstrong's comments by saying: "Ladies and Gentlemen, Mr Lance Armstrong - great at talking about it on a podcast, shit at actually doing it. On behalf of the peloton, thanks for the support."
One area that Millar has touched upon in his campaigning is the mental health of riders in retirement and ensuring the support networks exist to support riders in their lives after cycling.
The woes of Jan Ullrich have been well documented in recent weeks, as the German has spiralled into drug addiction and violence. Marco Pantani and Frank Vandenbroucke were two other high-profile riders who struggled with addiction, and died in 2004 and 2009, respectively.
"Those riders were all 'disgraced' by their countries and the press, while their countrymen, who weren't nearly as legendary as them, were given complete passes," said Armstrong, who recently went to visit Ullrich in Germany.
"This can feel really hypocritical and unfair. Throw in some guys who don't have the mental strength to manage it all and it's a recipe for disaster.
"The sample size of cyclists that took performance enhancing drugs is massive - in the tens of thousands - so if the tendency was to become an addict then we'd have hundreds if not thousands of addicts, which we don't. It's like the question I used to always get, did drugs cause my cancer? Same scenario - we'd have hundreds of guys with testicular cancer and we don't. We have two - Ivan Basso and me."
The CPA election takes place at the World Championships in Innsbruck on Thursday.