Byron York

But as much as he stressed federalism, Romney also stressed that he would be happy to see many states adopt his plan. "I think it's a good model for other states," he continued. "Maybe not every state, but most." At the federal level, Romney said he would "give every state the same kind of flexibility we got from the federal government." That's the Romney position, then and now.

But what about the different question of Romneycare in Massachusetts? On the day before the Las Vegas debate, The New York Times published a devastating story about the current state of Romneycare. Health costs in Massachusetts have risen steeply in the years since the introduction of Romney's plan. "Those who led the 2006 effort to expand coverage readily acknowledge that they deferred the more daunting task of cost control for another day," the Times reported, adding that Romneycare "did little to slow the growth of health costs that already were among the highest in the nation."

Now, with costs going up, the current Massachusetts governor, Democrat Deval Patrick, is considering a cost-control plan that could lead to the dreaded rationing, price controls and higher taxes.

The story seemed ready-made for one of Romney's Republican opponents, who could look Romney in the eye and charge that he had expanded coverage without regard to rising costs, leading to growing taxpayer subsidies and still more government involvement in health care. Former Sen. Rick Santorum tried to make just that case, but got so caught up in interrupting Romney that he failed to put forth a coherent argument. Other candidates intervened, and the question wasn't fully explored -- again.

If it comes up in future debates, Romney will likely argue that he's not responsible for what his successor does. But instead of fending off accusations about whether or not he intended it as a national model, Romney would be forced to discuss the actual workings of Romneycare. That hasn't happened very often, at least not yet.

Byron York

Byron York, chief political correspondent for The Washington Examiner