The full breakdown paralleled the opinions expressed by independent voters, 47 percent of whom said the law would harm the economy and 34 percent of whom said it would help.
Political partisans were less divided. Notably, Republicans were more confident in the law's negative impact (78 percent) than Democrats were in its positive one (62 percent).
Republicans have long argued that the health law is holding the struggling economy back and hope to rally their base around the issue before November.
One line of attack is the individual-mandate-as-tax — something the GOP has embraced despite a recent hiccup in which a senior adviser to Mitt Romney said his boss sees the mandate as a penalty.
This position was quickly reversed in an interview by Romney himself, who said on Wednesday that "it is a tax and it's unconstitutional."
Another recent poll found that a slight majority of political independents want Republicans to "move on to other national problems" and "stop their efforts to block the law."
That poll — from the Kaiser Family Foundation — found the public was evenly divided on the law, with 41 percent for it and 41 percent against it.