AP Photo/Charlie Neibergall

WASHINGTON (AP) -- The every-four-years ritual of a national "town hall" style debate began as a nerve-racking experiment in live television. Moderator Carole Simpson was so nervous about turning over the microphone to regular folks and their questions that she spent days mapping out the presidential candidates and their issues on "a zillion 3-by-5 cards," in case she had to take over the questioning herself.

"I was afraid these undecided voters from Richmond, Va., might get into this huge TV studio where they'd be seen by millions of people and they'd just freeze," the former ABC journalist recalls. "I wanted to be prepared."

No need to worry. The voters did fine. That "town hall" 20 years ago was such a hit that there's been one in every presidential election since.

The sixth will bring President Barack Obama and his Republican rival Mitt Romney to Hofstra University on New York's Long Island Tuesday night to take questions from undecided voters selected by the Gallup polling company.

Debate coach Brett O'Donnell, who worked with John McCain in 2008 and Romney during this year's primaries, says: "This is the one debate that belongs to the people."

It can be a tricky one for the candidates.

Obama, especially, needs a forceful showing to recover from his leaden performance in the campaign's first debate. But he must tread carefully in an atmosphere more suitable for share-your-pain moments than aggressive attacks.

"You can't have this sort of all-out slugfest at a town hall debate," O'Donnell said, so don't expect the fireworks of last week's Joe Biden-Paul Ryan vice presidential match.

Viewers want the candidates to show respect for those voters in the room, who stand in proxy for all Americans.

"You've got to connect with the person who's asking the question - look them in the eye," said Robert Denton Jr., head of the Communications Department at Virginia Tech. "It's about empathy and connection."

Romney comes to the arena strengthened by his first debate. And the people-first format gives him a unique chance to overcome a persistent weakness: suspicion among some voters that he's too wealthy to relate to the middle class and the poor. But if Romney fails to engage with his questioners, he could reinforce that impression.

That's what happened to President George H.W. Bush in the first televised town hall debate, a low moment in a failed bid for re-election. That 1992 event at the University of Richmond stands unmatched as an example of the format's risks and rewards.

Bush was thrown by a woman's oddly worded question: How had the national debt personally affected the candidates? He stumbled through a meandering response, asked the woman to clarify and ended up sounding irritated and a bit argumentative: "Are you suggesting that if somebody has means the national debt doesn't affect them?"

Even worse, just as she began her question, TV cameras caught Bush checking his watch.

That gesture would be replayed over and again as evidence that the president was indifferent and out of touch. "I took a huge hit," Bush said years later.

When Democratic challenger Bill Clinton got his shot at the same question, he set the standard for town hall emoting.

Clinton crossed the stage to stand before the woman, locked her in his gaze, and recounted the economic pain he'd personally witnessed as governor of Arkansas. "He just burst through the TV set," Simpson recalls.

How did that town hall come about? Not surprisingly, Bush had resisted the risky new idea. But Clinton pushed it in negotiations with Bush and the Commission on Presidential Debates because his campaign thrived on town hall-style events.

"It's the flesh and blood of America, so I love those things," Clinton later told Jim Lehrer of PBS. "And I loved that one."

Bush told Lehrer he hated debates, period.

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