WASHINGTON -- Barack Obama isn't used to hearing boos.

For all the young president's popularity, the response he got Monday from doctors at an American Medical Association meeting was a sign his road is only going to get rockier as he tries to sell his plan to overhaul the nation's health care system.

The boos erupted when Obama told the doctors in Chicago he wouldn't try to help them win their top legislative priority, limits on jury damages in medical malpractice cases.

US President Barack Obama delivers a speech on the health care system at the annual meeting of the American Medical Association in Chicago, Illinois, June 15, 2009. [Agencies]

But what could they expect? If Obama announced support for malpractice limits, that would set trial lawyers and unions -- major supporters of Democratic candidates -- on the attack. Not to mention consumer groups.

Obama can't give all of them what they want. Instead, he's got to figure what's just enough to keep as many groups as possible on board, without alienating others. It's a fine line for him, and sometimes for them.

"It's a coalition issue," said Robert Blendon of the Harvard School of Public Health, an expert on public opinion and the politics of health care. "No major group is able by itself to sink health reform. But if numbers of them come together for different reasons, it could really hurt the direction the president wants to go in."

The doctors were only Obama's first house call. He'll be making his case to the other groups, and to the nation at large, in an increasingly energetic campaign to get a bill passed by the end of his first year in office.

AMA insiders shouldn't have been surprised by Obama's upfront refusal to consider malpractice caps.

The group couldn't get that idea passed by a Republican Congress and president a few years ago. Some states have such curbs, but anyone who can count votes knows the chances for national limits are slim to none with Democrats in charge of Congress.

Instead, Obama left the door open to some kind of compromise on malpractice.