Most polling shows that Americans' opinions on Obamacare aren't changing — that people generally love or hate the law as much as they did when it passed in 2010. You see that in monthly polling from the Kaiser Family Foundation, as well as in a poll we did here at Vox last month with communications research firm PerryUndem.

That's what makes these results from YouGov a bit surprising: they do seem to indicate Americans warming up to Obamacare when you ask the question a slightly different way. Instead of asking whether Americans approve or disapprove of the health law, the YouGov poll asks if people think the law has been "more of a success" or "more of a failure." And the results show that over the past two years, more people consider the law a success:

The same trend shows up on a different question, about whether the health-care law ought to be repealed — or expanded or kept the same. Opinion in favor of expanding the law or leaving it as is keeps edging upward, and has actually now become a more popular option than repealing the law.

These charts by no means show that Obamacare has become a popular success — the first chart still shows there are more Americans who think the law is more of a failure than those who see it as a success. But they still show that some Americans' opinions are changing on the health-care law as it rolls out and covers more people.

Who's changing their minds? YouGov polling finds it's not Republicans becoming more positive, but rather Democrats who didn't like the law at first but are starting to warm up to it.

"One of the changes that has happened over the last few years is that Democrats have become more enthusiastic about Obamacare," YouGov writes in a summary of the findings. "In this week’s poll, six in ten Democrats say the ACA has been a success, while only one in ten Democrats call it a failure."