Rabobank ended the sponsorship of its cycling team last month because of the doping scandal that led to American rider Lance Armstrong being stripped of his seven Tour de France titles.
"I'm not surprised that Rabo went, naturally I'm disappointed for the sport," said Australian Jaimie Fuller, chairman of the SKINS sports clothing company that sponsors several teams and national federations.
"I know that there are other sponsors contemplating leaving and they are looking for some sort of reassurance that this isn't going to continue to happen. They are looking for reasons why they shouldn't leave," he added in an interview with Reuters.
The Armstrong affair is the latest and most serious of a series of doping scandals that have tarnished the image of cycling in recent years.
Sponsors must decide whether they believe cycling can finally rid itself of its doping problems or pull out of a sport that provides access to large and affluent television audiences.
Fuller was in London ahead of a meeting where he is bringing together a group of former riders and anti-doping campaigners who have united under the banner of "Change Cycling Now" to push for reform.
SKINS has filed a $2-million damages claim in Switzerland against the Swiss-based International Cycling Union (UCI), the sport's governing body, accusing it of mismanagement of the Armstrong case.
It has also said that UCI President Pat McQuaid and Honorary President Hein Verbruggen should step down.
Fuller said cycling had a unique opportunity to confess to past sins and that his company wanted to remain involved in the sport.
"If we can get it all out there and purge it and then bring in a new management with a clear goal of integrity then in three to five years' time the sport will be far more successful commercially than it is today," he said.
Britain's Team Sky, whose rider Bradley Wiggins won the Tour de France this year, has asked its staff to sign up to a written statement saying they had no past or present involvement with drugs.
Fuller said he applauded the sentiment but questioned whether that was the right strategy.
"I don't think we can find out what has happened in the past unless we are encouraging dopers and ex-dopers to tell us everything," he said.
"Unless there is some kind of truth and reconciliation process with amnesty powers, it ain't going to happen."
American Tour de France winner Greg LeMond and Jonathan Vaughters, manager of the Garmin-Sharp team, would attend the "Change Cycling Now" meeting in London, the organisation said.
The group plans to release a charter setting out its principles, aims and methods at a news conference when its meeting ends on Monday.