Most support expanding insurance, but they don’t know how the changes will affect them. The number one reason for that opposition: 81 percent think the law makes the wrong changes. And, 39 percent say the law would be “bad” for people like them, while 26 percent aren't sure.

These are the major findings in a just-released poll of 2,285 adults surveyed online between April 14 and 16 by Harris Interactive, one of the world's leading custom market research firms, and HealthDay, a leading producer and syndicator of health news.

Americans did come together – by a 58 percent to 24 percent majority – to agree that the legislation will provide many more people with health insurance. By 2019, an additional 32 million uninsured individuals will gain coverage, according to the Congressional Budget Office.

Another key feature is the legislation allows young adults to stay on their parents' health insurance plan until age 26, and that change takes effect this year.

"The public is divided partly because of ideological reasons, partly because of partisanship and partly because most people don’t see this as benefiting them. They see it as benefiting the uninsured," said Humphrey Taylor, chairman of The Harris Poll, a service of Harris Interactive.

Obama said his plan would "bring down the cost of health care for millions of families, businesses, and the federal government." But some have questioned the legislation's cost-containment provisions.

The poll found that more people think the plan will be bad for containing the cost of health care (41 percent to 35 percent), for strengthening the economy (42 percent to 29 percent), and for the quality of care in America (40 percent to 34 percent).