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Republicans hate Obamacare. Mitt Romney can’t stop defending it.

Not directly of course. But in Thursday night’s debate, just as in the one last week, Romney was confronted over his implementation of health care reform in Massachusetts that served in part as the blueprint for the Affordable Care Act. When Rick Santorum accused the ex-governor of supporting a “top-down government-run health care system,” Romney calmly explained that under his plan, Massachusetts residents were still purchasing private insurance. When Santorum reminded Romney that his plan compelled individuals without health insurance to buy it on “condition of breathing,” Romney gave an eloquent, if conservative, defense of the individual mandate:

[F]or the 8 percent of people who didn’t have insurance, we said to them, if you can afford insurance, buy it yourself, any one of the plans out there, you can choose any plan. There’s no government plan. And if you don’t want to buy insurance, then you have to help pay for the cost of the state picking up your bill, because under federal law if someone doesn’t have insurance, then we have to care for them in the hospitals, give them free care. So we said, no more, no more free riders. We are insisting on personal responsibility. Either get the insurance or help pay for your care. And that was the conclusion that we reached.

All of this can be said about Obamacare. It doesn’t “take over” the health care system, it regulates a health insurance market in which private companies compete. Individuals are compelled to buy insurance because, if they don’t, taxpayers ends up paying for their health care once they get sick. Romney simply can’t explain why Romneycare isn’t socialism without also explaining why Obamacare isn’t socialism. He can’t defend Romneycare’s individual mandate as an issue of personal responsibility without also doing the same with the individual mandate in the Affordable Care Act.

The strange part wasn’t that Romney offered this defense—after all, he’s done it before. It’s that when he offered it, the Republican audience actually applauded (via BuzzFeed).

Now, the Affordable Care Act is anathema to the Republican base. Every Republican candidate for president has vowed to repeal it. Yet framed in conservative terms, and defended by the likely Republican nominee, a Republican audience applauded its key concepts. Not every Republican loved Romney’s health care plan when it was implemented, but the perception of the Affordable Care Act as the twilight of freedom in America is largely a function of partisanship rather than ideology.

The mandate may not survive the Supreme Court. A recent Kaiser Family Foundation poll found that more than half of Americans think the mandate is unconstitutional, and the court is not immune to public sentiment. Partisanship is a powerful force, one that not only gives the Supreme Court popular cover for repealing the Affordable Care Act by fiat, but also will likely lead to the Republicans nominating Obamacare’s most eloquent defender.