In other words, Mr. Clinton counseled that independent voters might forgive Mr. Romney for having said whatever he had to say to win his party’s nomination, but they would be far more reluctant to vote for him if they thought they were getting the third term of George W. Bush. Ever since, the Obama campaign has been hammering Mr. Romney as too conservative, while essentially giving him a pass for having traveled a tortured path on issues like health care reform, abortion and gay rights. …

For a while this summer and into the fall, the Obama-Clinton strategy seemed to be working flawlessly. That’s because, almost inexplicably, Mr. Romney continued to run as if he were still contesting the Republican primaries. But in recent weeks, starting with the first debate, the challenger has made a brazen and frantic dash to the center, and Mr. Obama has often seemed off-balance, as if stunned that Mr. Romney thinks he can get away with such an obvious change of course so late in the race. Which, apparently, he can.

The bottom line here is that one can over-think this whole notion of framing your opponent. Ninety-nine times out of 100, the line of attack that works best is the one that really rings true. In the case of Mr. Romney, whatever his stated positions may be, the idea that he’s a far-right ideologue, a kind of Rush Limbaugh with better suits and frosty hair, just doesn’t feel especially persuasive.