"Defining Moment?"

E.J. Dionne (WaPo):

CHICAGO -- A dozen or so young staffers were gathered around a bank of television sets at Barack Obama's vast campaign headquarters here on Michigan Avenue. They were cheering on Rep. Adam Smith (D-Wash.) as he took their candidate's side in the great Obama- Hillary Clinton debate over how presidents should negotiate with unfriendly dictators.

The mood was upbeat not only because the Obama loyalists judged Smith the winner in his Wednesday clash with Rep. Steve Israel (D-N.Y.) on MSNBC's "Hardball," but also because Obama had pulled the front-runner into a direct confrontation over foreign policy.

Obama's own confidence was clear yesterday morning during a conference call announcing that he had won the endorsement of Rep. Paul Hodes, a freshman Democrat from New Hampshire.

Politicians often underscore their own virtues by discovering the same traits in others, and Obama is no exception. He praised Hodes, an upset winner in the 2006 elections, as "a fresh new voice" who "spoke the truth" and "believed he could be an agent of change." Hodes, right on message, explained his support for Obama as an effort to "complete my mission" in politics, which is -- you guessed it -- "to make some change."

And in response to questions, Obama continued to fire away at Clinton, saying her stand on negotiations with dictators was a continuation of "Bush administration policy." In the Democratic contest, those are fighting words.

The Obama-Clinton confrontation might easily be written off as midsummer meaninglessness. It was set off during Monday's CNN-YouTube debate, when the candidates were asked whether they would "be willing to meet separately, without precondition, during the first year of your administration . . . with the leaders of Iran, Syria, Venezuela, Cuba and North Korea, in order to bridge the gap that divides our countries."

Without hesitation, Obama replied: "I would." He dismissed as "ridiculous" the "notion that somehow not talking to countries is punishment to them."

Clinton sensed an opening. "I will not promise to meet with the leaders of these countries during my first year," she said, adding, "I don't want to be used for propaganda purposes."

Figuring she had the high ground, Clinton continued on the attack Tuesday, calling Obama's position "irresponsible and frankly naive." Instead of backing off, Obama fired back. On Wednesday, he hit Clinton on one of her weak points -- her 2002 vote to give President Bush authority to go to war in Iraq. "I think what is irresponsible and naive is to have authorized a war without asking how we were going to get out,' " Obama said. As some of us who watched "Batman" on TV remember: Kapow!

In fact, Obama clearly sensed his own vulnerability and quickly tried to cauterize it. He was careful to say repeatedly that in talking with Iranian President Mahmoud Ahmadinejad and other Muslim leaders, he would send them "a strong message that Israel is our friend."

He also pulled back ever so slightly, insisting that "the notion that I was somehow going to be inviting them over for tea next week without having initial envoys meet is ridiculous."

But the eagerness with which Obama's camp kept the battle going reflected a cardinal rule in politics: Front-runners should be wary of picking fights with challengers. In this case, Clinton allowed Obama to make one of her prime vulnerabilities, the Iraq vote, a central part of the campaign dialogue. She also let Obama place himself to her dovish side.

In a Democratic primary, that's not where she wants Obama to be. It was Obama's good fortune that as the controversy was building, Iowa Democrats were receiving a campaign mailing headlined: "Barack Obama said No to the war in Iraq from the start."

The most intriguing aspect of this controversy is that both campaigns were operating from their respective positions of strength. Clinton has successfully cast herself as the toughest candidate of the Democratic bunch and has Washington experience that Obama can't match. Obama, precisely because he exudes newness in so many ways, promises the most obvious break with the past.

If Obama wins the nomination, Republicans will try to make him pay a price for his negotiation-friendly attitude.

But this week, at least, Clinton started a battle about experience and Obama turned it into a debate about change.

This dynamic, over a stray comment in a single debate, could be remembered as the moment that defined the Democratic presidential contest. Clinton faces trouble if she allows Obama a monopoly on the future.