Eric Fehrnstrom's statement that individual mandates are penalties, not taxes, undercuts a key Republican talking point since the Obamacare ruling.

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Corrected, July 3

Chief Justice John Roberts didn't give conservatives the outcome they wanted in the Affordable Care Act case, but he did hand Republicans an excellent talking point to attack President Obama by declaring the individual mandate a tax.

For some reason, the Romney campaign is trying to hand it back.

MSNBC's Chuck Todd managed to back top Romney adviser Eric Fehrnstrom into a corner Monday morning, getting him to say that his boss does not believe the mandate is a tax, but is instead a penalty for "free riders" who don't want to buy insurance that helps subsidize the market. Here's a key portion:

Todd: The governor does not believe the mandate is a tax? That is what you're saying. Fehrnstrom: The governor believes that what we put in place in Massachusetts was a penalty and he disagrees with the court's ruling that the mandate was a tax. But again... Todd: But he agrees with the president that it is not -- and he believes that you shouldn't call the tax penalty a tax, you should call it a penalty or a fee or a fine? Fehrnstrom: That's correct.

This is only the latest example of Romney's struggle to attack a plan that is basically identical to the one he instituted in Massachusetts. He had to contend with all the same arguments -- after all, nobody ever wants a new tax, regardless of whether Democrats or Republicans are in power -- and has come up with most of the same answers that Obama has. He understandably doesn't want to say that he raised taxes as governor, but that means he has to either drop the tax attack against Obama or else just plainly contradict himself.