A Gallup survey of more than 1,000 U.S. adults found that 47 percent favor the repeal of healthcare reform, versus 42 percent who want the law kept in place. Eleven percent had no opinion.
But the survey also showed that 50 percent of Americans believe the federal government has a responsibility to make sure everyone has health coverage, compared with 46 percent who do not.
The results, which have a 4 percentage point margin of error, suggest a sharply divided U.S. public as the Supreme Court prepares to begin hearing legal arguments next March from 26 states and an independent business group that want the law struck down as unconstitutional.
The Patient Protection and Affordable Care Act would extend health coverage to more than 30 million uninsured Americans by expanding Medicaid and establishing special state-run insurance markets called exchanges.
The law is Obama's signature domestic policy achievement, and a high court decision to overturn the reforms could deal a severe blow to his re-election prospects in the middle of the 2012 presidential campaign. A ruling to retain it could help his campaign.
The Supreme Court would be expected to rule by July.
Obama, a Democrat, is opposed by a field of Republican candidates who want the healthcare reform law repealed as a symbol of an intrusive government seeking to raise taxes and burden businesses with new regulation.
But advocates of the reforms say the law will reduce the soaring growth of healthcare costs over time and provide medical care to millions of families who currently have no protection.
The Nov. 3-6 Gallup poll also showed a small reduction in public support for private insurance as the basis for gaining medical services in the $2.6 trillion U.S. healthcare system.
The findings said 56 percent of adults continue to prefer private insurance versus 39 percent who would favor a government-run system. That compares with a 61 percent to 34 percent margin a year ago.