WASHINGTON — What's it going to cost me?

Americans are worried about the fine print in the health care overhaul, an Associated Press poll says, and those concerns are creating new challenges for President Barack Obama as he tries to overcome doubts in Congress.

Despite a widely shared conviction that major health care changes are needed, Democratic bills that aim to extend coverage to the uninsured and hold down medical costs get no better than a lukewarm reception in the latest results.

The poll found that 43 percent of Americans oppose the health care plans being discussed in Congress, while 41 percent are in support. An additional 15 percent remain neutral or undecided.

There has been little change in that broad public sentiment about the overhaul plan from a 40-40 split in an AP poll last month, but not everyone's opinion is at the same intensity. Opponents have stronger feelings on the issue than do supporters. Seniors remain more skeptical than younger generations.

The latest survey was conducted by Stanford University with the nonprofit Robert Wood Johnson Foundation.

When poll questions were framed broadly, the answers seemed to indicate ample support for Obama's goals. When required trade-offs were brought into the equation, opinions shifted — sometimes dramatically.

In one particularly striking finding, the poll indicated that public support for banning insurance practices that discriminate against those in poor health may not be as solid as it seems.

A ban on denial of coverage because of pre-existing medical problems has long been one of the most popular consumer protections in the health care debate. Some 82 percent said they favored the ban, according to a Pew Research Center poll in October.

In the AP poll, when told that such a ban would probably cause most people to pay more for their health insurance, 43 percent said they would still support doing away with pre-existing condition denials but 31 percent said they would oppose it.

Costs for those with coverage could go up because people in poor health who'd been shut out of the insurance pool would now be included, and they would get medical care they could not access before.

"I'm thinking we'd probably pay more because we would probably be paying for those that are not paying. So they got to get the money from somewhere. Basically I see our taxes going up," said Antoinette Gates, 57, of Atlanta.

The health care debate is full of such trade-offs. For example, limiting the premiums that insurance companies can charge 50-year-olds means that 20-year-olds have to pay more for coverage.