"Well, this has been a tough campaign. It's been a very tough campaign. And I know from my experience in many campaigns that, if Sen. Obama had asked ... responded to my urgent request to sit down and do town hall meetings and come before the American people, we could have done at least 10 of them by now."

Thus did Sen. John McCain of Arizona, in Wednesday's third and final presidential debate, try to explain why the campaign had taken a nasty turn. If only Sen. Barack Obama of Illinois, the Democratic nominee, had agreed to appear in town hall meetings, McCain maintained, all the nastiness could have been avoided.

Somehow we doubt it, although it might have been an interesting experiment. But McCain is deluding himself if he thinks it would have helped his campaign. The more he has appeared on the same stage with Obama, the deeper the hole he has dug for himself.

Still, it hasn't been all his fault. A perverse form of luck has had something to do with it. McCain and Obama were virtually tied in mid-September when, just before the first scheduled debate, the financial markets collapsed. The Arizona senator had to go on television, a medium that is not his friend, to discuss economics, which also is not his friend.

It is said of Napoleon that when his aides recommended officers for promotion, the first question he would ask was, "But is he lucky?"

Obama is lucky. The Illinois senator also is calm, deliberate and unflappable. McCain, on the other hand, is wound very tightly, a bundle of energy. One is cool; the other is hot. And television — in the classic terminology of Marshall McLuhan — is a "cool" medium, one in which viewers prefer to fill in their own blanks.

No matter what format the debates followed — standing at podiums, as in the first debate on Sept. 26; a faux town hall gathering, as in the second debate on Oct. 7, or seated at desks as in Wednesday's affair — cool played better than hot.

In this, McCain was doubly handicapped on Wednesday evening. His advisers and his instincts had primed him to vilify Obama for his relationships with a former 1960s domestic radical and his support for the community organization group ACORN — two hot-button issues for the GOP base.

The base likes heat. Moderate voters don't. And they especially don't like heat punctuated with smirks, rolling eyes, ferocious blinking and a classic trick from the Karl Rove playbook: When cornered, accuse your opponent of doing what you're actually guilty of: running a negative, nasty campaign.

Obama's calm reply was devastating: "I think the American people are less interested in our hurt feelings during the course of the campaign than addressing the issues that matter to them so deeply."

And then, driving the stake home, Obama said, "What the American people can't afford, though, is four more years of failed economic policies. And what they deserve over the next four weeks is that we talk about what's most pressing to them: the economic crisis."

In the end, the Obama-McCain debates may turn out to have played a larger role in this election than in any other presidential contest since the practice began in 1960. It will be recalled that political professionals thought Richard Nixon, for all his death's-door appearance in the first debate, actually won all four debates that year.

But the folks at home, drawing their impressions from the images delivered by the youthful medium of television, liked the cool young senator from Massachusetts, John F. Kennedy. At least one veteran politician at the time —. Nixon's running mate, Ambassador Henry Cabot Lodge — got it. After watching Nixon on the televised debate, Lodge turned to a companion and said, "That son-of-a-bitch just lost us the election."

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