has to win this one if for no other reason than pride, and the president’s supporters seem increasingly confident that he will do well. But when I ask them what “well” would look like, what they imagine when they imagine his victory, they’re not sure. They don’t say things like, “The president knocks him out in the first round,” or “The president wears Romney out with successive tough questions and answers.”

It’s a tough format. No one knows what to expect.

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The rough circumstances going in:

The last time Mitt Romney and Barack Obama debated, the press was itching to write the Romney Comeback story. Now they’re itching to write the Obama Comeback story. This matters because people tend to see what they expect to see and have trouble seeing the unexpected even when it unfolds before their eyes.

The hardest thing about the debate for Mr. Obama is that he really needs to bring it to Mr. Romney, to push and challenge—but it may be difficult to find and hold the exact degree of aggression required because both men, in the town hall format, will be surrounded by an audience of happy Americans. I don’t suppose a politically mixed audience of voters wants to see an American president snarl, slice or attack. He will have to find the sweet spot and throw consistent hardballs but not beanballs.

The hard things for Mr. Romney will be winning for a second time in a row, and winning so vividly that his victory is clear in the coverage. Last time he surprised a lot of people. This time his competence and command won’t come with the force of a discovery. It will be factored in. If Mr. Romney has a good night it will be because we’ll know, within a day or so, that his first victory was not a fluke. The second debate will be absorbed by viewers as more proof that he’s a pair of safe hands, a person who could be trusted with the presidency.

*   *   *

The president’s overall imperative is to erase the memory of the Oct. 3 disaster. He has to make people forget it. He has to blur the memory by providing a new memory: Obama engaged, Obama attractive, Obama in the moment, Obama responding with confidence and challenging his opponent. Obama replying with wit, or with soft, sure indignation, to something Romney said that he believes not to be true.

So the president has to erase and replace. That’s hard.

Mr. Romney doesn’t have to erase, only reinforce. He doesn’t come in as a stranger now. Seventy million Americans met him in a new way two weeks ago, and he impressed them. He has to hold his ground. He cannot let up on his challenges to the president. In his courteous way, he will likely lay out the essentials of what hasn’t worked the past four years, and why and how he can turn it around.

*   *   *

A guess on how it will go? Mr. Obama will attempt to seize and establish momentum and command early. Mr. Romney will expect this and be ready. Mr. Obama will throw out a charge or a challenge, Mr Romney will answer and try to turn it around into a countercharge, a counterchallenge. Both men will want to engage with the audience, but Mr Obama needs to most urgently: If he shows a high comfort level with the people in the hall, and gets them smiling or nodding, it will suggest to viewers watching on TV that the president has a friendly relationship with the American people. Boy, does he need to demonstrate that!

There won’t be any stalking on the stage, à la Al Gore in 2000. But how each candidate holds himself, what physical attitude he takes, will be noticed and commented upon later.

I wonder if the campaign in Chicago thinks Mr. Romney has a glass jaw? I wonder if they’re thinking he can’t take a series of hard hits? I wonder how many times the phrase “the 47%” will be used? I wonder if Mr. Romney will answer—with “No, 100%” or “No, I care about all the people.” Meaning I wonder if he knows that on this issue he should steer clear of words like “percent.” What lines has Mr. Obama practiced to suggest Mr Romney believes in nothing, has changed his mind on central issues and so cannot be depended upon?

*   *   *

This time, say his supporters, the president has taken debate prep seriously. This time he knows his friends are nervous. This time he can’t just try to crowd-surf on a nonexistent wave, he’s got to fight.

It is not likely he’s been demoralized by the Oct. 3 disaster. He’s probably been focused by it. He loves to compete. He’ll enjoy hearing the “Obama Comeback” stories, and in a way they’re already being written, because that’s the moment in the narrative we’re at: the comeback story. It will be almost as much fun for the mainstream press to write as the disaster story.

*   *   *

One thing Mr. Romney might properly accentuate:

Mr Obama will probably claim, and legitimately, what he always claims: that the day he walked into the White House, he was faced with a true economic catastrophe, one left to him by a Republican administration. The president may also say he’s worked as hard as he could and can name some progress—and this in spite of a Republican Party that wouldn’t work with him.

He always says this; he believes it is true.

A thing that is not pointed out often enough is that in his first year, Mr. Obama was in a brilliantly promising political position. He had a Democratic House and a Democratic Senate, he had sky-high poll ratings, he was hailed throughout the world, and he had the latitude—the latitude—iimparted by crisis. His political opponents were demoralized. The American people would have given him a lot of running room to come up with and institute new programs and approaches on joblessness and the debt, the two essential and growing issues of the moment. Instead he took his first two years and went on a long strange trip in which he gave all his time and attention to a vanity production called ObamaCare. It was a huge, lumbering, barely coherent, anxiety-inducing and expensive program, and the American people hated it—still hate it. The president didn’t understand his moment. He didn’t understand the depth and duration of the economic crisis. This was the fatal mistake of his administration. At bottom it’s the central critique of his leadership.

As for the Republicans who wouldn’t work with him, there are always people in the other party who say they’ll never work with you. You have to scare them into line. That’s what presidents do. They go over the heads of Congress and the media and straight to the people, in TV addresses, and they win the support of the people—”This is what I’m doing, this is why, this is why it will help, please give me support and please tell your senators and congressmen to support me.” Suddenly senators and congressmen start getting told when they’re back in the district, “I like our fella there in the White House, help him out.” Tip O’Neill didn’t run into the Reagan White House, fling himself into Ronald Reagan’s arms and say, “Where’s the scotch? Let’s talk turkey and make progress for our nation!” He got scared into it. His own conference members were telling him what they were hearing back home.

Why didn’t Mr. Obama go over the heads of the Congress to the people? Or, actually, why did he do it a few times and it didn’t work, and nothing moved in Washington, and everything stayed stuck?

More to the point, why did the president not spend the past 3½ years meeting with Republican Congressional leaders, or even that many Democratic leaders? Because he doesn’t like people that much? That’s an odd thing in a political leader. Did this personal idiosyncrasy become an actual political dynamic, the thing that more than anything else led to the current stasis? Everybody in Washington talks about this. Maybe it should be aired, as courteously as possible, in our next-to-last presidential debate.