BOSTON (Reuters) - The organizers for Boston's campaign to host the 2024 Olympic Games on Monday said they would not make a final bid to the International Olympic Committee unless a majority of Massachusetts residents support the idea.

The vow, which came in a full-page ads in the Boston Globe and Boston Herald newspapers, comes days after a poll showed that a majority of Boston-area residents opposed the idea, with many concerned that city taxpayers would be left to cover some of the estimated $9.5 billion costs of hosting the Summer Games.

"There are legitimate concerns and potential risks associated with this effort that must be addressed in a thoughtful and transparent manner for the Games to work for Massachusetts," the Boston 2024 committee said in the ad.

The group did not specify how a majority support would be measured, whether through a ballot initiative or by polling. Failed 2014 gubernatorial candidate Evan Falchuk already has called for the question of whether to host the Games to be put to a statewide vote.

In January the U.S. Olympic Committee picked Boston over rival cities including Los Angeles and Washington, D.C., to bid for what would the first Olympics in the United States since the Salt Lake City Winter Games of 2002.

Even before the pick was formally made, an organized opposition had sprung up to oppose the idea, contending the crowds of spectators, athletes and media would overwhelm Boston's aging transportation infrastructure and the city would be unable to bear the costs of hosting the event.

The IOC is expected to pick a host city for the 2024 Olympics in 2017. Boston's bid would pit it against cities including Hamburg and Rome, and possibly Paris, Doha or Istanbul.

(Reporting by Scott Malone; Editing by Bill Trott)