Athletes have urged the International Olympic Committee to raise the minimum number of sports needed to stage a Summer Games from 15 to 25.
Baseball and softball are currently not part of the 2012 programme
The Athens Games in 2004 featured the maximum of 28 sports.
Softball and baseball were taken out of the 2012 schedule at an IOC meeting in Singapore in July but no sport received the necessary votes to replace them.
Athletes now fear there is nothing to prevent the number of sports being brought down to the minimum of 15.
Former pole vault great Sergei Bubka, chairman of the IOC's athletes' commission, said he had asked their Executive Board to raise the minimum number allowed.
"Since Singapore there has been a lot of discussion about this," he said.
"We lost two sports in Singapore but you didn't see anyone get in. This has created a lot of concern and worries from athletes."
Sports hoping to make their Olympic debut, including rugby sevens, golf, squash, karate and roller sports, were unable to get a two-thirds majority of Olympic members but Bubka wants a change to that rule.
"We have to be realistic," he said. "Two-thirds was difficult to achieve. A simple majority would give sports more of a chance."