Strict Rules Behind Debate's Looser Town Hall Format Stephen D. Crowley/The New York Times George W. Bush and Al Gore during their town hall debate in 2000. The format has produced some curious moments. The format for the second presidential debate is designed to be a little less stiff - a free-flowing question-and-answer session between the candidates and a studio audience. But behind the scenes, little is left to chance. There are 80 participants, culled by Gallup, the polling firm, from a sample of uncommitted voters who live near the debate's location in Hempstead on Long Island. On Tuesday morning, they are scheduled to arrive at the site to begin rehearsals with the moderator, CNN's Candy Crowley. They will have prepared questions to ask but will not use them during the prep session. To preserve as much secrecy as possible, they will rehearse with dummy questions. Ms. Crowley will select the participants to call on during the actual debate, which she will determine by reviewing their questions beforehand. The campaigns are not allowed to screen any of them. There are strict time limits and rules. After the audience member asks a question, his or her microphone will be immediately shut off. The candidate will have two minutes to answer. The other candidate is then given two minutes to respond. Then the moderator will be able to pose a follow-up question of her choosing, with each candidate allowed one minute to respond. Though organizers have taken many steps to minimize surprises, town hall debates have produced some of the more memorable and mockable campaign moments. Often candidates seem to get tripped up by the freedom of motion the format allows. It was during the 1992 town hall hosted by Carol Simpson that President George Bush was caught looking at his watch. And this was no mere peek. He stood up from his stool, raised his arm so he could see his wrist and then adjusted his pants, a move critics and comedians alike seized on as evidence that he was detached and dismissive. In 2000, Vice President Al Gore walked across the stage and stood uncomfortably close to George W. Bush, which prompted a puzzled-looking grimace and a nod from his opponent that drew laughs from the audience. And in 2008, Senator John McCain made liberal use of the floor space. "The Daily Show" mocked him as appearing confused and even scripted this question as part of a fake inner monologue: "Has anyone seen my dog?" Erica Berenstein contributed reporting.