National Review‘s reaction to Mitt Romney’s health care presentation was largely in line with most conservatives: the editorial board isn’t happy.

“[W]hen conservatives argue that Obamacare is a threat to the economy, to the quality of health care, and to the proper balance between government and citizenry, we do not mean that it should be implemented at the state level,” the conservative magazine argued today. “We mean that it should not be implemented at all.”

This wouldn’t be especially noteworthy, except for the fact that National Review endorsed Romney’s presidential campaign in the last cycle. Matt Yglesias flagged the 2007 piece, which said:

Our guiding principle has always been to select the most conservative viable candidate. In our judgment, that candidate is Mitt Romney, the former governor of Massachusetts. Unlike some other candidates in the race, Romney is a full-spectrum conservative: a supporter of free-market economics and limited government, moral causes such as the right to life and the preservation of marriage, and a foreign policy based on the national interest. […]

Like any Republican, he would have an uphill climb next fall. But he would be able to offer a persuasive outsider’s critique of Washington. His conservative accomplishments as governor showed that he can work with, and resist, a Democratic legislature. He knows that not every feature of the health-care plan he enacted in Massachusetts should be replicated nationally, but he can also speak with more authority than any of the other Republican candidates about this pressing issue.

The point, of course, is that Romney — despite being a legendary, unrivaled flip-flopper — hasn’t actually shifted much when it comes to health care policy. He supported his Massachusetts law before, and he supports his Massachusetts law now.

The problem is that Romney’s party has changed. Indeed, National Review has run into the same problem Sen. Jim DeMint (R-S.C.) has — namely, that many of the conservatives who endorsed Romney in ’08, in part because of his success on health care, have discovered they can no longer tolerate the policy they used to find impressive.

I’m not in the habit of defending Mitt Romney, but the onus shouldn’t be on him to disavow his own success; the burden should be on his conservative critics to explain why they oppose policies they supported a few years ago.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.