The International Olympic Committee will decide in July whether to add any new sports to the 2012 Olympics.
Greco-Roman wrestling is one of the sports thought to be in danger
President Jacques Rogge said there would continue to be 28 sports, but the future of each will be decided by 117 eligible voting delegates.
To remain in the programme, a sport must receive at least 51%.
Golf, rugby, karate, squash and roller sports are pressing for inclusion, but would have to receive a two-thirds majority vote if a vacancy arose.
In 2002, Rogge proposed that baseball, softball and modern pentathlon be removed, and golf and rugby added, but IOC members resisted and no vote was taken.
Voting will now be based on a list of criteria including global popularity, ticket sales, attendance figures and television ratings.
Other sports thought to be at risk of exclusion are fencing and Greco-Roman wrestling.
The 2008 Beijing Games will not be affected, and will feature the same sports as Athens last year.