Over the weekend, I watched the 2008 town hall-style debate between Barack Obama and John McCain. And while it's true that Obama won that debate, it was mostly because John McCain was terrible at it. Whenever McCain was stressed, he addressed the audience as "my friends," and it almost immediately became an off-putting vocal tic. He seemed to wheel around in circles when talking to the audience, looking at everyone and doing a tone-deaf parody of Bill Clinton's warm, inclusive debate style.
But Obama wasn't very good at the town hall format, either. He mostly delivered chunks of his speeches whenever someone asked a question, and he didn't provide very many anecdotes or very much personal warmth at all. The thing that every candidate should keep in mind during a debate is that the audience is part of the set. You want the audience to appear engaged with everything you say, and the way to do that is not by speechifying at them.
Back when the presidential campaign was small and regional, Mitt Romney hosted a series of events called "Ask Mitt Anything." It's true that it was a friendly audience, but the events were basically one-man town halls, and Romney did well at them. He was a little stiff, but he did the job. I bet he'll be even better at it tonight.
Romney's biggest weakness in these situations is that he doesn't do well with direct confrontation. If he gets tough questions from the audience and if President Obama calls out some of Romney's more obvious lies, the older, stiff Romney might make a reappearance. That should be the president's goal. But President Obama can't be totally aggressive, the way Biden was with Ryan. He'll have to walk a fine, lawyerly line, which is a problem when his instincts veer more toward the professorial. On the positive side, President Obama is a smart guy, and he basically devoted the entire weekend to town hall debate prep. I'd just feel better if John Kerry wasn't involved in the president's debate prep. The man is like a walking bad luck charm for Democrats.