On Friday evening in Oxford, Miss., Barack Obama and John McCain will meet in the first presidential debate of 2008, and this dramatic campaign will in all likelihood reach another turning point.
The matchup could have come much earlier, but Obama turned down McCain's invitation to join in a series of joint town hall meetings during the summer. That would have allowed both men to ease into personal confrontation with relatively small audiences and similarly modest stakes.
Now, they meet with terribly high expectations on both of them and little room for error. McCain, after enjoying a brief boost in his fortunes from the Republican convention and the unveiling of Sarah Palin, has fallen back into his pre-convention position, lagging slightly behind. Obama still is unable to lock down 270 electoral votes, because he is falling well short of the lead that Democrats enjoy generically over the Republican opposition this year.
Obama is known for his eloquence, while McCain often struggles even when given a decent script to read. That creates an expectation that the Democrat ought to dominate when the two men are directly compared.
But when I discussed the coming debate with one of the Democrats' most experienced debate handlers - a man who helped prepare Hillary Clinton for the primary debates and now is advising Obama - he said, "No matter what others say, I think this is a very even matchup."
McCain, he said, has developed a knack for answering questions with flat, simple declarative sentences, conveying a sense of candor and strength. Obama, on the other hand, often starts slowly and finishes with a more complex, if sophisticated, answer. That made McCain the clear winner when they did back-to-back sessions with pastor Rick Warren.
When I bounced these comments off a Republican counterpart to the man just quoted, he was derisive. "That's spin," he said. "McCain has lots of strengths, but verbally, he's not in the same league as Obama. This will be a severe test for him."
Looking back at the performance of the two men during their primary debates, the proposition that they are evenly matched looks quite plausible.
McCain began his revival last year with a strong performance in a Republican debate in New Hampshire. Throughout the spring, he was usually at least the second-best man on the stage, outdone by the folksy and humorous Mike Huckabee but clearly more comfortable and assertive than Mitt Romney, Fred Thompson, Rudy Giuliani and the others.
Except for Romney, McCain was rarely directly challenged in the way that Obama will test him; the other Republicans paid tribute to his character and treated him with kid gloves. So his struggles to maintain his composure and avoid personal attacks on Romney suggest a potential vulnerability in the Arizona senator. When Obama bluntly questions McCain's positions, the Arizona senator may have difficulty staying cool.
On the other hand, Obama did not win the Democratic nomination by dominating the debates. In the early ones, when the stage was full, he lacked the verbal or physical tools to stand out from the crowd. More often than not, it was Hillary Clinton or John Edwards who made the strongest impression on the cameras and the audience. And when Clinton and Obama met one-on-one, she won most of the confrontations and the subsequent primaries.
The scheduled topic for the first debate is national security. We know that McCain will fault Obama for his opposition to the "surge" strategy and Obama will question why McCain was an enthusiastic backer of the Iraq War, which Obama opposed from the start.
But the real test for both men is different than this argument. To win the election - and not just this debate - McCain must somehow convince voters that he would be fundamentally different from George Bush, whose policies and methods have been overwhelmingly rejected.
To win the election - and not just the debate - Obama must show enough of himself that voters come to believe that despite not being able to identify with aspects of his exotic life story, they can trust him to look out for their interests as president.
Those are very different challenges. Neither candidate has an easy task. That is what makes this debate so intriguing.
E-mail nationally syndicated columnist David Broder at email@example.com.