Late last month, just before the convention, Obama led Romney by just 1 point on healthcare, 49-48.
Democrats launched an unusually sustained embrace of the Affordable Care Act during their convention. Although Obama himself didn't mention it by name, he mentioned some of its most popular provisions and repeated the Democratic attacks on Romney's Medicare proposals, which would partially privatize the program.
Public opinion of the healthcare law is deeply divided and leans negative, but this is isn't the first poll to show Obama with a consistent lead on the overall issue. A recent Kaiser Family Foundation survey put Obama up by double digits on healthcare issues, including Medicare and Medicaid.