Every presidential nominee faces a similar problem: In the primaries, you have to appeal to your base voters, tickling the tender parts of the ideological true believers, but in the general election, you need to appeal to independents, necessitating a move to the center. The transition from one to the other can be awkward. In the last few days, I've heard a number of Republicans give the same answer when this question is brought up. Isn't their eventual nominee being hurt by the fact that their primaries involve a lot of things like immigrant bashing and coming out against contraception? Nah, they reply, it'll all be OK—after all, Barack Obama and Hillary Clinton had a hard-fought primary in 2008, and he still won easily in the fall. I suspect we'll be hearing this many times over the next few months, so let me explain why it's completely mistaken.
Obama and Clinton did indeed have a hard-fought primary. It was vigorous, at times even a little ugly. But there's one thing it never was: A contest over who was the most ideologically extreme.
That isn't to say Democrats didn't talk amongst themselves about which candidate was the truer liberal. They did. A lot. I'll confess that I was one of the many who ended up believing, with only the most limited evidence, that Obama would display far more fealty to progressive principles than Clinton would, a belief that turned out to be misplaced. I even once wrote that I thought that on health care, Clinton would see the public option as nothing but a chip to be bargained away, while Obama would fight to keep it (ha!).
But with the exception of a couple of brief moments (like when Clinton criticized Obama for praising Ronald Reagan), that discussion didn't come from the candidates themselves. There were no Clinton ads saying, "Hillary Clinton: The true liberal." Or Obama ads saying, "Barack Obama: Liberal values, a record of liberalism." Their campaign, when it got beyond the day-to-day squabbles, was what then-editor of The American Prospect Mark Schmitt called the "theory of change primary"—not about who was the most liberal in their hearts, but about which method of politics would produce the kind of results they agreed on.
There may be almost no difference between what Mitt Romney and Rick Santorum actually propose to do once each becomes president. But they and the other candidates have spent the last few months saying, in full view of the entire electorate, "I'm the most conservative!" "No, I'm the most conservative!" You've got ads like this one, in which Santorum attacks Romney for his prior liberal positions, and ends with the tag line, "Rick Santorum: A trusted conservative." You've got this Ron Paul ad saying Santorum's a "fake conservative." You've got Mitt Romney feeling so much pressure that he has to proclaim that as governor he was "severely conservative." All that produces headlines like this one: "Romney, Santorum battle over who's more conservative."
So the nominee, most likely Romney, will have to distance himself from all that once the fall comes. And quite conveniently for Barack Obama, that will necessitate some ideological squirreliness that will reinforce exactly the critique the Obama campaign will be making of his character.