Some 43% of those surveyed now support the law, while 45% oppose it, the poll found. Last months 50% supported it while 35% were opposed.
Despite the change, the poll found health care is not an important election issue:
Registered voters remain split in three roughly equally-sized groups: voters likely to oppose a candidate who supported the law; those likely to support a candidate who backed the law, and those who say their vote won't be affected one way or the other.
Republicans respond that the "enthusiasm gap" in their favor, the likelihood of Republicans to be more enthusiastic about voting this year than Democrats, means the issue will play well for them.
This is borne out by the poll:
Republicans have an edge in intensity: 62 percent feel "very" unfavorably toward the bill, compared to 33% of Democrats who feel "very" favorably, according to the poll.
The poll was taken August 16-22, among a representative sample of 1,203 adults, most of whom said they were registered to vote. The margin of error is plus-or-minus 3%, slightly higher when subgroups are reported.
In a separate story, a Democratic Congressman who supports the law in Virginia said the tone in his town hall meetings has shifted, with fewer questions about principles and more questions about details. "Health care is not going to get you," concluded Rep. Gerry Connolly.
But the economy might.