* Candidates charge bias, producers struggle for fairness
* No prepared notes allowed, pens and pads provided
By Patricia Zengerle
LAS VEGAS, Oct 18 (Reuters) - Participants in Tuesday's Republican presidential debate will take part in a classic American political ritual, where the questions are closely vetted for fairness and even the pens and bottled water are regulated.
Good debate performances can boost or break a candidate's White House chances so staffers fret over every detail -- not just whether their candidate is ready for tough questions but also which tie will look best against the backdrop.
When they take the stage at a Las Vegas casino hotel, seven Republicans vying for their party's nomination to challenge Democratic President Barack Obama in the November 2012 election will be at identical podiums, placed to correspond precisely to their standing in national opinion polls.
The candidates with the highest average percentages in public opinion surveys since Sept. 1 will be in the center and the laggards in the polls will speak from the ends of the line. Their audience will be 1,200 delegates to the Western Republican Leadership Conference, the debate co-sponsor with CNN.
"The candidates will have at their podium a pad of paper supplied by CNN, a pen supplied by CNN, a bottle of water supplied by CNN and an empty glass provided by CNN," said Sam Feist, executive producer of the Las Vegas debate for CNN.
"At all of our debates we ask the candidates not to bring any notes into the debate hall but they're welcome to write anything they like on their pads of paper and all the podiums are set up in exactly the same way," he said.
The questions, which will come from journalists and voters, have been pored over by the network's political team. Candidates pick their own outfits, CNN the makeup artists.
Each debater is meant to get same number of questions. But front-runners tend to spend more time on the air, because they are more often the subject of attacks by their competitors. Some candidates also just choose to speak more than others.
GAFFES 'REPLAYED AND REPLAYED'
Candidates are quick to point fingers if they feel they do not receive their fair share of attention. Supporters of Texas congressman Ron Paul lashed out after earlier debates for what they deem deliberate neglect.
"Clearly he's not getting his fair share," said Jesse Benton, national chairman of Paul's campaign. "You're looking at a guy who is number three in polling and he's dead last in air time. And that's a travesty."
Few events on the U.S. political calendar are as fraught as televised debates, starting with the first between John F. Kennedy and Richard Nixon back in 1960. Radio listeners thought the vice president defeated Kennedy but television viewers said the handsome young senator won.
"Press coverage and talk about (debates) is entirely influential," said Kathleen Hall Jamieson, director of the University of Pennsylvania's Annenberg Public Policy Center. "There's a press consensus after each debate of who did and did not do well and if you've done something that is foolish or inept, it's replayed and replayed and replayed."
This year, Texas Governor Rick Perry's poll numbers slumped after a string of unimpressive debates. Conversely, businessman Herman Cain, an experienced radio host, leaped in the polls after strong debate performances.
Candidates prepare differently. Some hire coaches and hold mock debates with staffers. Paul, 76, always exercises. "He'll get in a bike ride tomorrow," Benton said.
Preparation consumes an enormous amount of time and distracts from more traditional campaign activity like formulating policy proposals, said Republican strategist Ford O'Connell, a veteran of John McCain's 2008 campaign.
This year, with so many debates, the final "winner" might merely be the last man standing, not necessarily the best candidate to defeat Obama, he said.
"It has really become politics' version of the reality TV show 'Survivor,'" O'Connell said.
(Additional reporting by Karen Brooks in Austin, Texas; Editing by Mary Milliken and Bill Trott)
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