With only about five minutes to go in the sober Democratic debate Thursday night, it seemed there would be no memorable moment, and thus no winner.

Then Barack Obama suddenly showed why he is the surprise of the political season. With a strong voice and a confident, focused look, he returned to a question about a hypothetical terror attack on two U.S. cities to deliver a mini lecture about the need for a president to be willing to use our military might. Saying we face “a profound security threat,” he shattered the developing anti-war tenor of the debate to say there “is no contradiction” in using diplomacy and the military.

That he immediately became the target of the two oddball candidates, Dennis Kucinich and Mike Gravel, both of whom accused him of being too ready to fight, put Obama in a good light. He was able to pivot off their extremism to show himself a pragmatist on the most important issue facing America.

On the basis of that brief but spirited exchange, where he became the focal point of the debate, the Illinois senator scored just enough points to come away the narrow winner.

His performance, which was otherwise uninspired, should keep him close to Sen. Hillary Clinton for the top spot in the primary field.

Especially because Clinton was off her game. Like Obama, she started out with tentative responses to moderator Brian Williams’ questions, and while she became increasingly forceful, she never got in a groove.

And her tactic of turning every question, even ones on hedge funds and Wal-Mart, into an attack on President Bush was too obvious and heavy-handed to be successful.

Because she focused more on what she is against instead of what she is for, I learned nothing new about her ideas on anything of substance.

Worse, she was classically evasive on Iraq, and not very clever about it.

Asked at the outset if she agreed with Senate Majority Leader Harry Reid’s statement that “the war is lost,” Clinton filibustered but never gave a clear yes or no answer.

Asked about her own vote supporting the war in 2003, she repeated by rote her line that, “It was a sincere vote based on the information available to me. And I’ve said many times that if I knew then what I now know, I would not have voted that way.”

Later, asked what mistakes she had made in public life, she fell back on the fiction that I find especially maddening: the claim that she didn’t really vote for the war, she just voted to send inspectors back to Iraq. Her mistake, she said, “was believing the president” wanted the war resolution for that purpose.

As I have written before, it is an outrageous lie. Congress considered three other Iraq resolutions in 2003, all of them more restrictive than the one Bush wanted, and Clinton voted against all three. And in the five months between her vote and the invasion of Iraq, not once did she object to the war. It was only when the war became unpopular that she and her husband began to try to rewrite the history of her vote.

Still, my guess is that the debate will not alter the dynamics of the race, with Clinton, Obama and John Edwards remaining the top three. The party’s large anti-war bloc already opposes Clinton, dividing its support between Obama, who always opposed the war, and Edwards, who supported it but has said he was wrong.

Clinton’s best hope is that both men stay in the race and continue to divide her opponents.

Judging by her performance Thursday night, that might be the only way she can win the nomination.