Updated

By Gene Cherry

RALEIGH, North Carolina (Reuters) - The doping cases that have dogged athletics leave it at risk of being overtaken by swimming as the premier Olympic sport.

"Because of the drug issues, because it (athletics) is not terribly compelling, I think swimming has taken over a little bit in terms of Olympic sports popularity," Bob Dorfman, creative director of San Francisco's Baker Street Advertising and a nationally recognized sports analyst, told Reuters in a telephone interview.

His comments came in the wake of Olympic and world 400 meters champion LaShawn Merritt's admission through his lawyer on Thursday that he had failed three dope tests for a banned substance contained in an over-the-counter male enhancement product he had taken.

The positive, which is under investigation by the U.S. Anti-Doping Agency (USADA), will have a key impact on the sport both financially and audience-wise, analysts and sports officials said.

"These stories always amount to a huge setback in keeping the sport relevant to people who barely care to begin with," Paul Swangard, managing director of the University of Oregon's Warsaw Sports Marketing Center, said in a telephone interview.

"It is the type of thing that contributes to a general reluctance by fans and ultimately to sponsors.

"Every time the sport seems to be poised to hit the mainstream, these types of revelations tend to set the sport back further than other sports because there is so much history with past issues related to performance enhancing substances," Swangard added.

FOLLOWERS CYNICAL

Merritt, 23, is the latest high-profile U.S. athlete to fall foul of the dope testers.

The public's image of the sport really took a nose dive when disgraced sprinter Marion Jones lied about taking drugs, Dorfman said.

"That probably was the biggest blow and I think that has made most followers of the sport cynical," he said.

Jones was stripped of her three gold and two bronze medals from the 2000 Olympics after admitting using banned drugs following years of denial. She also served a six-month U.S. prison sentence for lying to federal prosecutors about her steroid use.

Former 100 meters world record holder Tim Montgomery and 2004 Olympic champion Justin Gatlin have also been suspended for doping violations.

The impact of his case will go far beyond Merritt, said Doug Logan, chief executive officer of USA Track and Field (USATF).

"Actions like this are costing them (athletes) paydays," Logan said in a telephone interview. "It is this kind of behavior that diminishes the value of the sport in the commercial world.

"I am not planning any sponsor calls in the next 48 hours," he added.

"However disappointing this news is, the image of athletics should be strong enough to survive," Nick Davies of the International Association of Athletics Federations (IAAF) said in an email to Reuters.

"Sponsors and fans will appreciate that the sport has no mercy when it comes to hunting down those who break anti-doping rules," Davies said.

"The alternative is not to try to catch the cheaters and that is the end of a credible sport."

(Editing by Alison Wildey. To query or comment on this story email sportsfeedback@thomsonreuters.com)