But while both sides arrived in here in a brawling mood — with McCain, in particular, under growing pressure to bloody Obama — aides and advisers to both candidates say that tonight's town-hall-style debate is no place to throw a punch.
"There's a lot of talk about nastiness and personal attacks, but in this type of format, that is a huge mistake," said Bob Barnett, a Democratic lawyer who negotiated the debate's ground rules on Obama's behalf. "You have to be respectful to the audience questioners, you have to be respectful of the Internet questioners, and you have to have the viewers who are watching feel that you are responding to the voters and the citizens who are asking the questions."
McCain's top strategists also acknowledge the format doesn't lend itself to sharp-edged attacks.
"You have to strike a balance between responding to the questions asked and being responsive to people in a town hall but also and contrasting your record with your opponent," said Matt McDonald, a senior McCain adviser. McCain aides said they didn't expect McCain to raise Obama's relationship with the former Weatherman bomber William Ayers, unless it came up.
The setting at Belmont University puts the members of the audience — uncommitted likely voters — center stage. Moderator Tom Brokaw of NBC will select from their questions and from questions sent over the Internet. The candidates will respond, but aren't permitted to roam the stage.
That setup comes at a bad time for McCain, who trails in national polls and has seen the electoral battlefield shift almost exclusively to states that he was expected, a month ago, to win handily. He and his running mate, Sarah Palin, have campaigned recently in Florida and Nebraska and will soon even have to fly into North Carolina and Virginia. McCain's core message, meanwhile — that Obama is an unknown, untrustworthy quantity — has been drowned out by the continuing fall of the Dow Jones Industrial Average and Americans' fear of the consequences of economic crisis.
At the Belmont debate, Obama and McCain face different challenges. For Obama, it's the kind of informal setting in which he has, at times, put off audiences by answering emotional, personal questions with arid abstractions. McCain, by contrast, is most at ease in the town hall setting but must rein in an apparent disdain for Obama that was visible, and damaging to the Republican, in the first debate. He must also use the debate to reassure voters that the doubts about his temperament — Obama has called him "erratic," and he has been testy in recent interviews — are misplaced.
"The debate is in Nashville, so McCain should light a guitar on fire and smash some amplifiers. No reason now to hold anything back. He's at his best when he's talking directly to voters and incorporating his famous wit and humor," said Mark McKinnon, a Bush adviser in 2000 and 2004 and, until earlier this year, a full-time McCain strategist: "He should stroll the stage and own it like he's on the deck of an aircraft carrier. This is a real opportunity for McCain to remind Americans what they liked about him all along."
Another Republican strategist, Mary Matalin, said McCain needed to use the debate to increase the contrast between the candidates and "reinforce the risk [of Obama] and his own superiority."
McCain's campaign is optimistic that the familiar setting — the same one the Arizona senator proposed to hold regular forums in earlier this summer — will serve it well and portray the improvisational McCain at ease and the more scripted Obama, less so.
"It should accrue to our benefit," said McDonald. "When Barack Obaa has to go off script, it has the potential to be a good moment for us."
Though the format doesn't make it easy, McCain's goal, said McDonald, is to remind voters of "the difference between what Barack Obama says and what he's done. That's the fundamental contrast for the closing 30 days."
Obama's aides, meanwhile, have also been talking up McCain's strength in town hall settings. Happy with the outcome of the last debate — in which some analysts scored McCain a winner on points but in which Obama's open demeanor, compared with McCain's apparent edge, left voters favoring Obama's performance — they're hoping for a contrast of temperaments as much as of ideas.
Obama's press secretary, Bill Burton, used a pre-debate memo to reporters to stress McCain's lack of warmth in the first debate and to preempt a negative strategy.
"We don't know if McCain will continue his refusal to even look at Obama on stage — like in their first debate — but we fully expect that his 'turn the page' strategy to ignore the economy will be seen in full view for 90 minutes of character attacks against Barack Obama," he wrote.
Obama spokesman Robert Gibbs said Obama could talk about Charles Keating, the McCain supporter whose involvement in the savings and loan crisis tarnished the Arizona Republican.
"If people want to get down into the mud, we're prepared to get dirty, if that's what it takes," he said.
But neither candidate seems to be preparing attacks in a debate that will be, most of all, an empathy contest. In a format similar to the 1992 debate in which Bill Clinton stole the show by feeling voters' pain, two men who aren't particularly good at hugs or prone to tears will have to show not just that they understand the questions, but also that they grasp the feelings behind them.
"There is only one question in a town hall debate: Do you get it? A town hall is about empathy more than experience or intelligence," said Paul Begala, a former adviser to Clinton. "If you want to get their votes, you've got to feel their pain."