For starters, now we've seen just how much a debate can change the race. And all eyes will be on President Obama to see if he can improve his performance from the first debate Oct. 3 in Denver.
The president's team is promising a more "energetic" performance.
Obama was criticized for not matching Mr. Romney's aggression in the last debate – but in a town-hall debate, where the emphasis must be on answering voters' questions in a personal, direct style, it can be harder to find opportunities to engage aggressively with the opposing candidate.
Since "town hall" debates were introduced 20 years ago, they've been a fixture in every presidential election season.
Here's what to expect:
• The audience will be made up of about 80 undecided voters, screened and selected by Gallup, the polling organization.
• Audience members will each submit questions in advance to moderator Candy Crowley, of CNN, and Ms. Crowley will choose which audience members to call on. Each candidate has two minutes to respond, and there will be an additional minute for Crowley to facilitate discussion. The audience member who asked the question is not permitted a follow-up.
• Each candidate will get two minutes for a closing statement.
Still, even with rules hashed out in detail, some controversy has arisen during the past week – and it's unclear, at this point, how much leeway Crowley has to press the candidates or to ask a follow-up question.
According to Time magazine's Mark Halperin, the agreement worked out between the two campaigns stipulates that Crowley has a very limited role that bars her from intervening in the debate beyond calling on the questioners and keeping the candidates to their two-minute time limit.
Crowley, on the other hand, apparently views her role differently and doesn't feel bound by the agreement hammered out by the campaigns and the Commission on Presidential Debates. On Oct. 5, speaking on CNN, Crowley said, "Once the table is kind of set by the town-hall questioner, there is then time for me to say, ‘Hey, wait a second, what about X, Y and Z?’ ”
On Tuesday morning, she reiterated that sentiment on CNN, pointing to the additional minute for the moderator to facilitate discussion between the candidates. "There's time for a follow-up question, facilitating a discussion, whatever you want to call it," Crowley said. "If 'Alice' asks oranges, and someone answers apples, there's time to go, 'But Alice asked oranges. What's the answer to that?' "
Both campaigns are reportedly alarmed by her statements and have pushed back – but are also operating under the assumption that Crowley may play a greater role in the debate than they'd like.
In the last town-hall presidential debate, in 2008, moderator Tom Brokaw was criticized by some people afterward for rephrasing many of the questions and asking too many of his own follow-up questions.
The very first televised presidential town-hall debate in 1992, between Bill Clinton, George H.W. Bush, and Ross Perot, had even fewer rules. None of the questions was screened beforehand, and moderator Carole Simpson had no idea what each person might ask. That first debate still boasts the most indelible town-hall debate moment, which undoubtedly stands as a reminder to Romney and Obama of both the risks and opportunities on Tuesday night.
A woman asked the candidates how the national debt had "personally affected" each of them. It was an odd question, and then-President Bush stumbled through his response, first looking at his watch, and then faltering as she kept pressing him to state his answer in more personal terms. Finally he blustered, "Are you suggesting that if somebody has means the national debt doesn't affect them?"
Mr. Clinton, on the other hand, took a different tack. He walked over to the woman, looked her in the eye, and launched into an eloquent speech on the people he knew who had lost their jobs or been harmed by the recession, before segueing into the choice he saw voters had in how each candidate planned to improve the economy.
It was a stand-out moment for Clinton, who radiated empathy like no one else and for whom the intimate town-hall style allowed him to showcase that quality and to connect with voters. Mr. Bush's fumbling of the question – and the fact that he checked his watch as she asked it – made him seem out of touch with average Americans, a stereotype he was already fighting.
The town-hall format – whatever Crowley's role turns out to be Tuesday night – is much more scripted now than it was then, and it is doubtful that such a poorly worded or vague question would be allowed. But the format still tends to make for interesting television, and for more unexpected questions – and answers – than in a typical debate.