"There needs to be some other mechanism for people ... to have a way to get coverage, other than through employers," Greenstein says.
Since its passage, the law has struggled to win public support. The latest USA TODAY/Gallup Poll found Americans disapprove of the new law 56% to 39%, though the Kaiser Family Foundation has found that many individual provisions are more popular.
"The White House and its allies won the legislative debate. They lost the debate in the court of public opinion," says Robert Moffit, director of the Center for Health Policy Studies at the conservative Heritage Foundation.
Obama is likely to address the law next week as its earliest provisions — including one allowing children to remain on their parents' policies until they turn 26 — start taking effect.
At the same time, Republicans in Congress led by Rep. Steve King of Ohio are mounting an uphill drive to repeal the law. Others, such as Sen. Tom Coburn of Oklahoma, threaten to block funds needed to implement it.
Opponents in several states are challenging — in courts and legislatures and at the ballot box — the law's mandate that most people buy insurance. They say people should not be required to have health insurance and states should not be required to pay additional costs not covered by the federal government.