David Brooks notes this morning that Barack Obama may have fallen into a trap:
[A]t different times during this election, he’s been told to get off the white horse and start fighting. In the current issue of Time magazine, Michael Duffy and Nancy Gibbs report on a meeting that took place in Chicago last Labor Day. All of Obama’s experienced advisers told him: “You gotta get down, get dirty, get tough.”
Obama refused. He argued that if he did that, the entire basis for his campaign would evaporate. “If I gotta kneecap her,” he said, “I’m not gonna go there.”
And, for a time, it worked, but things are different now. Clinton’s victories on Tuesday have re-made the race yet again and, given that neither one of these candidates can win the nomination outright before the convention, Obama has no choice:
The Obama people seem to have persuaded themselves they can go on the attack, but in the right way. They can be tough and keep their virginity, too. But there are more than five long months between now and the convention.
Unless they consciously reject conventional politics, the accusations will build on each other. The BlackBerries will buzz. The passions will rise. The Obama forces will see hints of Clinton corruption all around, and they’ll accuse and accuse again. The war will begin to take control, and once you’re halfway through you can’t suddenly surrender because it’s become too rough.
And the Clinton people will draw them every step of the way. Clinton can’t compete on personality, but a knife fight is her only real hope of victory. She has nothing to lose because she never promised to purify America. Her campaign doesn’t depend on the enthusiasm of upper-middle-class goo-goos. On Thursday, a Clinton aide likened Obama to Ken Starr just to badger them on.
As the trench warfare stretches on through the spring, the excitement of Obama-mania will seem like a distant, childish mirage. People will wonder if Obama ever believed any of that stuff himself. And even if he goes on to win the nomination, he won’t represent anything new. He’ll just be a one-term senator running for president.
And if that happens, Clinton might just win this.

