For years my son's favorite book was Watership Down, in which the novelist Richard Adams richly imagined the language and world view of a band of rabbits. Among the mostly puzzling and frightening "man-things" to the rabbits is the automobile, the hrududu. At night, says one rabbit, that terrible device reveals "great lights" that "draw creatures toward them and if they shine on you, you can't see or think which way to go. Then the hrududu is quite likely to crush you."

I'm beginning to think that Barack Obama is the hrududu of American politics. Opponents see him coming, become confused, and charge right under his wheels. Even when they escape with their lives, the next time his great lights shine over him they do it again. Sooner or later they get flattened, although he never swerved an inch off his course.

Hillary Clinton, for one, seemed to take forever to understand that her own current campaign strategy was flattening her. After her aloof, inevitable-winner style failed her in Iowa, she made her surprising New Hampshire comeback through a more compassionate, more earnest connection with her voters, climaxed by her famous near-tears moment. Then she and her husband squandered her new momentum with a nastiness that squashed her in South Carolina and clearly soured her supporters. She quickly went back to being compassionate, earnest and scrupulously respectful of her opponent (and near tears again), and on Super Tuesday again did better than most of the late polls were predicting.

You would think that a canny politician (which, by all evidence, Clinton has been for decades) could immediately see the pattern: optimistic and heartfelt works. Negative and arrogant hurts. But in the headlight-glare of Obama's huge wins in Virginia and Maryland, she pulled a confused rabbit maneuver: straight back into nastiness and spurious accusation in Wisconsin. And again, she lost. Though "lost" is not a big enough word. Despite last-minute polls showing a close race, she managed to lose by a crushing 17 percentage points. She lost 61 counties and won 10. She lost every demographic group except people over 65.

At this point you would expect even the less-than-canny politician, even the thick-headed politician, to get the message. Nice: do okay. Nasty: lose. At this point you would assume she would roll back to the compassionate, the earnest, the optimistic, the respectful. Instead, Hillary Clinton did the opposite—at least in the immediate aftermath. She increased the ferocity of her attacks, rolling out the same charges that backfired horribly in Wisconsin. So disastrous did her strategy seem to many of her own supporters that they quickly formed the American Leadership Project, a "527 group," to produce pro-Clinton advertisements that are promised to be "positive" and "focused on issues." It's said that they won't even mention Obama. 527 groups have been more commonly used, as in the case of the Swift Boat Veterans who attacked John Kerry, to say vicious things about an opponent that a candidate fears might be too unsavory to be associated with. In this case, Clinton's own campaign had become so unsavory that her supporters had to strike out on their own to try to save her from herself. Not until Thursday night's debate did she seem to have reconsidered.

The mesmerizing power of Obama's campaign is less about him than the nature of his support. A majority of American citizens, including an overwhelming majority of those younger than Hillary Clinton, have clearly decided that they are sick of the politics of hostility. And when they are confronted with it, they get mad—not at the object of the hostility but at the source. Politicians like Clinton, raised in the self-righteous rage of the Baby Boom and trained by the last 16 years of divide-and-conquer strategies, don't know what to do with that. They have it in their heads that the smear campaign is the big gun, the tactic to reach for when they really want to put an opponent away. In frustration, fear, anger, self-pity, that's all they can think of. They react as instinctively as rodents facing lights that they have not evolved to understand. The voters who have bonded with Barack Obama largely because he doesn't campaign that way don't have to veer off course to hit them. They just keep rolling.

Now John McCain has shifted his attention away from his beaten Republican rivals and turned his eyes toward the Obama campaign. At first he could only stare into those huge, blazing lights bearing down on him. But now he's made his jump: straight for the wheels.

For McCain to emphasize Obama's lack of experience makes perfect sense. When you're 71 and your opponent is 46 it's the natural place to start. But the way McCain chose to do this was a grotesque distortion of Obama's comments on how he might handle a hypothetical situation involving Pakistan, a distortion that becomes embarrassingly obvious as soon as you read the original quote. It's always good, too, if you can catch your opponent "waffling" or "flip-flopping." Unfortunately, the arena in which McCain has chosen to fight that battle is public campaign financing. And although he may score a point or two in suggesting that Obama's changing his mind about an old decision, every time he raises the issue he essentially requires the press to remind us that the reason this matters so much to him is that he doesn't have a chance in hell of ever raising a fraction of the money that Obama can raise. There it is in every story: in the month that McCain pulled $11 million out of a smallish number of wealthy backers, Obama raised $36 million from hundreds of thousands of voters across America.

The message is clear: McCain wants to handicap Obama because he can't compete. Not the message you want to launch your campaign with. But when those headlights hit you, what can you do?