Barack Obama had a theory. It was that the voters are tired of the partisan paralysis of the past 20 years. The theory was that if Obama could inspire a grass-roots movement with a new kind of leadership, he could ride it to the White House and end gridlock in Washington …

Yet at 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.” …

Beneath the euphemisms, what the advice really means is that Obama has to start accusing Clinton of things …

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 …

In short, a candidate should never betray the core theory of his campaign, or head down a road that leads to that betrayal. Barack Obama doesn’t have an impressive record of experience or a unique policy profile. New politics is all he’s got. He loses that, and he loses everything. Every day that he looks conventional is a bad day for him.

Besides, the real softness of the campaign is not that Obama is a wimp. It’s that he has never explained how this new politics would actually produce bread-and-butter benefits to people in places like Youngstown and Altoona.

If he can’t explain that, he’s going to lose at some point anyway.

Read it all: http://www.nytimes.com/2008/03/07/opinion/07brooks.html?_r=1&hp&oref=slogin