A new study finds that although the public remains stubbornly split on the Affordable Care Act, a slight shift may be occurring beneath the surface — with a growing minority of people coming around to the opinion that the law is having a real impact on access to health care.

To be clear, the analysis is based on two-year-old data, and it shows more people are opposed to the law (45.6 percent) than in favor of it (36.2 percent). It also shows that most Americans — albeit a shrinking majority — still think the law has had "no/little impact" on any of the following: increased access to health care, insurance coverage for young adults, assistance for drugs to seniors or insurance subsidies. What the study published Wednesday in Health Affairs did find is a suggestion of a possible emerging contradiction in public opinion: a growing appreciation of the law's effects, even as the overall approval of the law itself remains stubbornly divided.

"We’re assuming people are kind of locked in the usual Hatfield-McCoy partisan disagreement, but actually as the law is put into place, we’re seeing individuals kind of coming to follow their concrete interests — what they and their families and friends are experiencing," said Lawrence Jacobs, a professor at the Humphrey School of Public Affairs at the University of Minnesota.

The new study took a different approach than a typical poll, returning to the same national sample of 1,200 people in 2010, 2012 and 2014 to assess any changes in their opinions of the law and its effects. Only about half of that sample responded all three times, but that novel structure meant the poll could track how opinions evolve over time.

While the new study found that the split over approval of the law didn't change much over four years, breaking down the data showed some changes in how people perceived its effects. There's been a 19 percentage-point increase in people who say the law is increasing access to medical care and insurance.

People who had health insurance in 2014 but were uninsured in 2010 were more than twice as likely to say they thought the law had expanded access compared with a group that did not gain insurance.

And among those who oppose the law, there has traditionally been overwhelming agreement about what should happen, with more than 80 percent in favor of repeal in previous surveys. Of those opposing the law, the proportion in favor of repeal dropped modestly to 72 percent in 2014.

The Kaiser Family Foundation has polled on the popularity of the ACA regularly and more recently, and found the approval of the law fairly stable over time, like the new study. A January poll, however, found contradictory results about support for repeal, finding that support for repeal of the law has remained stable over time.

What Jacobs's statistical analysis of the data reveals is that partisanship, trust of government and entrenched opinions formed at the time the law was enacted seem to explain the opposition to the law writ large — while personal experience, such as gaining insurance, is leading more people to report that the law is having an impact on health-care access.

Jacobs argued that the data suggests if politicians were not so ferociously against the ACA, it would quickly become popular, "because it's already registering with people — and the bulwark against its popularity is partisanship and distrust in government," he said. But his data also shows how much negative opinion there is left to erode, with the majority opinion being that the law has had "no/little impact" on a variety of measures of access.