It’s hard to fathom that any candidate won over big chunks of the electorate in Tuesday’s Democratic presidential debate — other than perhaps Dennis Kucinich, the new darling of the Roswell crowd as the first 2008 presidential contender to admit seeing a UFO.

But this was a debate that was more about campaign tactics than policy differences — in particular on what all of these challengers were going to do to stop Hillary Clinton’s march to the nomination. They got an assist from moderators Brian Williams and Tim Russert, who directed what seemed like the bulk of the queries to all things Hillary.

“This is where everybody plays gotcha,” she said at one moment of queries.

Chief among the candidates in taking on Clinton were Barack Obama and John Edwards, who proved that if they could not change the dynamics of the race they could at least change the dynamics of a debate.

One after another, they and Joe Biden, Chris Dodd and Dennis Kucinich challenged Hillary the front runner, as if MSNBC teleprompters signalled “Target: Woman in Pantsuit.”

Leadership, Barack Obama said, “does not mean changing positions when it is politically convenient.”

“Now, that may be politically savvy, but I don’t think that it offers the clear contrast that we need,” he said.

And at one point, Obama said, “Part of the reason that Republicans, I think, are obsessed with you, Hillary, is because that’s a fight they’re very comfortable having. It is the fight that we’ve been through since the ’90s.”

He challenged her positions on social security, NAFTA and her vote for a resolution declaring Iran’s Revolutionary Guard Corps a terrorist organization.

But you could still feel a twinge of discomfort from Obama in taking such an approach, often pausing as if choosing his words carefully. Even he himself signaled that all of the attention on his amping up his attacks was overhyped, using a “Rocky” reference that ultimately fell flat.

Instead, his attacks were upstaged by Edwards’ attacks. He was more specific, more strident, more biting in his criticism of Clinton, at one instance standing by his claim that she was engaged in “doubletalk.”

On her vote on the Iran resolution, Edwards said, “I mean, has anybody read this thing? I mean, it literally gave Bush and Cheney exactly what they wanted.”

He was perhaps the most aggressive in picking apart Clinton’s plan to end the war in Iraq.

“She says she will end the war, but she continues to say she’ll keep combat troops in Iraq and continue combat missions in Iraq. To me, that’s not ending the war; that’s the continuation of the war.”

Clinton held her own, but did so by directing her attacks at President Bush, not the other Democratic candidates. In fact, she rarely mentioned them by name. Speaking a few decibels higher than normal, it was as if she were merely doing another round of “Meet the Press,” controlling the message when she could, dodging questions when necessary. She wasn’t too clear on whether she’d issue drivers licenses to illegal immigrants, but it’s hard to believe that will be a central issue of the campaign.

Edwards has vowed to have all combat troops out by the end of his first year in office. Clinton said, “I stand for ending the war in Iraq and bringing our troops home, but I also understand that it’s going to take time.” But she added that some troops must remain to fight al-Qaida.   

On Iran, she said, “In my view, rushing to war—we should not be doing that—but we shouldn’t be doing nothing. And that means we should not let them acquire nuclear weapons, and the best way to prevent that is a full court press on the diplomatic front.”

Others were critical, too. Dodd said the resolution could be used by Bush to pursue a war. Biden said that the Iran resolution has “emboldened” Bush and has perhaps contributed to the rise in gasoline prices.

The sparring became forceful enough — I have seen worse, mind you — that Bill Richardson stepped in to call a truce, and then used the opportunity to underscore the fact that he’s the one with the real experience as a governor, a.k.a. “CEO.”

“We need to stay positive,” he said.

That didn’t apply to Republican candidates, however. Once again garnering the line of the evening, Biden took on Rudy Giuliani’s foreign policy experience,  “There’s only three things he mentions in a sentence: a noun and a verb and 9/11. I mean, there’s nothing else. And I mean it sincerely. He is genuinely not qualified to be president.”

The candidate who got hit with a true zinger was not Clinton, Edwards or Obama but Kucinich. As the debate was wrapping up, he was asked whether Shirley MacLaine’s story was right — that he had seen a UFO while visiting her at her home. He did.

“More people in this country have seen UFOs than I think have seen a probe of George Bush’s presidency,” said Kucinich.

And who says celebrity endorsements don’t matter?