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They're not an official category of voters whose tally is measured in exit polls, like whites or blacks, women or men, old or young. And since they're not an official category, we may never really have the evidence.
But I have a feeling I know which group really handed Hillary Clinton - or maybe they were thinking even more of that other Clinton - her decisive loss to Barack Obama in South Carolina on Saturday night. Call them "high-information Democrats."
These are the people who follow all the ins and outs of the contest. They read The New York Times. They watch cable television, probably Keith Olbermann first and foremost. They read blogs. They know every twist and turn, every thrust and parry. And yes, they exist even in South Carolina.
As I said, they are not a measured category. But Obama was ahead by eight to 15 percentage points in most public opinion polls up to Friday. He won by more than that, 28 percentage points. Who accounted for this disparity? We'll need to see raw turnout numbers by region to have a better idea - according to one network exit poll Obama won a majority of college-educated voters, both white and black. I suspect that it's a plausible conclusion that high-information voters swung in Obama's direction in the contest's closing days and hours.
If I'm right, those voters were pretty clearly saying that they didn't like the kind of campaign the Clintons were running against a fellow Democrat. It's a rebuke for both Clintons that will force them to rethink their scorched-earth strategy toward Obama and that presents them with a conundrum.
Hillary Clinton lost Iowa resoundingly. After that defeat, her team obviously decided that it was time to stop limiting itself to the polite pointing out of differences and go all-out against Obama, with the former president taking the lead in making the attacks. Whatever one may think about the propriety of a former president injecting himself so sharply in an intra-party fight, the strategy paid dividends in New Hampshire and Nevada.
But now, the strategy has backfired in a big way. The Clinton camp was saying as recently as Thursday that, while Bill might be a bane as far as the elites were concerned, he was boon as far as rank-and-file voters were concerned. But is that so clear now? I don't think so.
So here's the spot the Clintons are in. They can't run a comparatively "nice" campaign, of the kind they were running in Iowa, because that risks a repeat of the Iowa defeat in some of the February 5 states. However, they also can't go too negative, because that may move high-information voters - and there are more of them, percentage-wise, in the crucial February 5 state of California - toward Obama.
So they have to walk the razor's edge of finding exactly that point on the spectrum that isn't Iowa -- nice but isn't South Carolina -- nasty.
That means, first and foremost, figuring out how they can rein in Bill Clinton, which is no easy task. But it also implies a broader rethinking of a strategy that has aggressively sought to convince Democratic voters that Obama just isn't qualified to be president. That latter strategy failed. Numbers don't lie: voters in two states out of four have concluded that he's just as qualified as Clinton is.
Race? Of course it was a factor. Obama obviously benefited from the fact that the South Carolina vote is half African American. But I've always felt that what the media called a racial fight was also about other things â€” "race" is one of those red-flag words that the media love to latch on to and can't let go. But by mid-week, the race debate had really turned into a referendum on the Clintons' comportment. A large number of voters said: cool it.
It's worth remembering that Hillary Clinton still has the advantage on February 5. She most likely has a win wrapped up in her adopted home state of New York. She probably has the neighboring, also-delegate-rich state of New Jersey. She's well ahead in the mother-lode state, California. She's ahead in Missouri. She's even ahead in states that Obama "ought" to win February 5, such as Alabama and Tennessee.
Obama has lots of work in front of him. He needs, I think, a little magic in California (will Senator Barbara Boxer endorse him? Just idle speculation, but keep an eye on it). He will have to win most of the February 5 southern states, or the pundits will regard South Carolina as a fluke.
But make no mistake. The message out of South Carolina is that the Clintons overplayed their hand. Can they do humble? That's just one among many fascinating questions that will settle a contest that is far more invigorating and challenging than Democrats had any reason to anticipate.