ONE SIDE EFFECTIVELY DEFINED OBAMACARE. ONE SIDE DIDN'T. GUESS WHO WON.

A new poll from the Kaiser Family Foundation shows that the public's feelings about Obamacare are more changeable than most people think:

Public Easily Swayed On Attitudes About Health Law, Poll Finds

... minimal follow-up information can have a major effect on their viewpoint, the poll found.

For example, when people who support the "employer mandate" were told that employers might respond to the requirement by moving workers from full-time to part time, support dropped from 60 percent to 27 percent. And when people who disapprove of the policy were told that most large employers will not be affected because they already provide insurance, support surged to 76 percent.

Opinion also remains malleable about the requirement for most people to have health insurance – the so-called "individual mandate."

It remains among the least popular aspects of the law – with just a 35 percent approval rating. But when people are told that the mandate doesn't affect most Americans because they already have coverage through an employer, support jumps to 62 percent. Conversely, when supporters are told that the requirement means some people might have to purchase insurance "they find too expensive or don’t want," opposition grows from 64 percent to 79 percent....

Think Progress responds to this with a cheery headline: "The More People Are Told About Obamacare, The More They Like It." That's not really true -- the big shifts in opinion go both ways. That's for an obvious reason: The law is complicated. People have busy lives and haven't studied it, so when they're told something new about it, it's no surprise that they might change their minds.

But that's been the problem for President Obama and congressional Democrats: Republicans and their media allies have done an excellent job of getting out detailed negative information on Obamacare (accurate or otherwise), while the president, Democrats, and the progressive media have done a lousy job of getting out detailed positive information. In fact, you could say that the worst thing about Nancy Pelosi's "we have to pass the bill so that you can find out what is in it" soundbite is not that it described a strategy of concealment (it didn't), but that it described a surrender in the messaging wars -- what Pelosi was saying, in effect, was that Democrats couldn't possibly out-message Republicans while the bill was making its way through Congress, so they weren't even going to try. And they didn't try very hard afterward, either.

And that's why Obamacare is unpopular, even though people don't really understand it: There was a message war, and Republicans won in a rout. I disagree with Jonathan Bernstein's take on this poll:

What this tells us is that we should approach claims about public opinion and health care reform with caution. Saying "Obamacare polls badly" or "the individual provisions of the ACA other than the individual mandate poll well" isn't the same as saying "Obamacare is unpopular" ...

It's likely, though still not certain, that most people just don't have opinions about either the program or its various parts. That's normal; most of us don’t bother to form real opinions about many things, even though we are willing to answer polling questions.

Sorry, but no -- Obamacare is unpopular. People have opinions about it; those opinions can be changed, but the handful of Obamacare skeptics who sat through this Kaiser poll are among the few doubters who've ever had the program's positive aspects explained to them in a forum where they're likely to pay attention. Negative messaging on Obamacare, by contrast, is ubiquitous. (Someone at my office has an anti-Obamacare coffee mug, for crissake.)

Referring to the Kaiser poll, Bernstein adds:

And if these findings are correct, then I'm even more skeptical that it was opposition to Obamacare, and not feelings about President Barack Obama, that drove Republican election gains in 2010 and 2014. Yes, as political scientist Matthew Dickinson mentioned in a recent post, some studies purport to show that Obamacare, specifically, cost Democrats quite a few seats in 2010 (I don't think anyone has run numbers for 2014 yet). But I've been very skeptical of that finding. In particular, it's extremely likely that if Democrats had ignored health care in 2009-2010 some other program would have symbolically done the same work. That is, Republicans would have replaced attacks on Obamacare with additional attacks on the stimulus, bailouts or Dodd-Frank. But really, voters were just reacting to Obama, his job performance and the economy.

Well, yes, the attacks might have been on another Obama program -- because Democrats would have been out-messaged on that program, too.

So how did Obama win in 2012? He won by doing a better job of messaging -- since 1992, Democrats have been pretty good at doing this in presidential campaigns, and only in presidential campaigns. They needed the equivalent of a presidential campaign to sell Obamacare; they needed to have campaign-style rapid-reaction responses to Republican attacks on health care reform. That never happened. And so, on Obamacare public opinion, Republicans won.