(Repeats to add full coverage link) For full coverage on healthcare reform click [ID:nN02516257]

* Obama compares healthcare system to GM

* Hits out at critics of public insurance plan

* Says plan will keep insurance companies "honest" (Updates with share movement, CBO report)

By David Alexander

CHICAGO, June 15 (Reuters) - President Barack Obama warned doctors on Monday the U.S. healthcare system was a ticking time bomb and urged them to support his overhaul, which includes a public insurance plan that many of them view with skepticism.

Obama took his healthcare campaign to the annual meeting of the influential American Medical Association, which represents 250,000 doctors and has historically been opposed to a bigger government role in healthcare.

"If we do not fix our healthcare system, America may go the way of GM; paying more, getting less, and going broke," Obama said, likening the healthcare system to struggling carmaker General Motors, which has filed for bankruptcy protection.

"Make no mistake: the cost of our healthcare is a threat to our economy," said Obama, who wants a healthcare reform bill on his desk by October. [ID:nN15221549]