More than three weeks before Sen. Joe Biden, D-Del., and Gov. Sarah Palin, R-Alaska, were set to meet in St. Louis for their Oct. 2 vice presidential debate, Biden was already predicting a messy fight.

"She's going to make it as personal as she can. She's going to take a lot of straight lefts and jabs at me, she's going to try to get me to respond in a personal way," Biden told a Chicago audience. "That's not my style. I'm not going to do it."

Throughout September, staffers and allies were prepping candidates for the three presidential debates and the one VP debate that could produce the decisive moments within a tight struggle. Biden, for example, tapped Michigan Gov. Jennifer Granholm to stand in for Palin during debate rehearsals. Despite sharp ideological differences with Palin, Granholm bears some similarities to the candidate: She is a 49-year-old governor with three children. (Palin, 44, is a first-term governor with five children.)

Considering Biden's 30 years in the Senate, and previous presidential runs, Palin faces a formidable match. Saint Louis University political scientist Ken Warren compared the contest to another epic battle: "The vice presidential debate will attract a lot of interest because of David, so to speak, going up against Goliath."

In the center ring, Sen. Barack Obama, D-Ill., and Sen. John McCain, R-Ariz., are facing the weightiest political bouts of their careers as well: three televised debates on Sept. 26, Oct. 7, and Oct. 15. As the debates unfold before an estimated 70 million viewers (more than any other televised event outside the Super Bowl), how will the candidates spar? What should viewers look for, and how will they know who wins? And what does a candidate's debate performance say about the kind of leader he or she might be?

For those with ringside seats or living room views, here's a guide to the matches of the year.

The history

Television viewers watched presidential candidates slug it out live for the first time in September 1960, when Vice President Richard Nixon and Sen. John F. Kennedy met for the first of four televised contests dubbed the "Great Debates."

The Kennedy/Nixon match-ups revealed at least one thing about televised contests: image matters. Nixon, who appeared pale and slightly unshaven, was also recovering from a knee injury that left him fatigued and thin. Kennedy, who had spent the first two weeks of September campaigning in California, appeared tan and fit.

Many who heard the first debate on the radio declared Nixon the winner. But by the end of the fourth televised contest, Kennedy's visual style and political substance delivered a one-two punch that Nixon couldn't match. Kennedy and others later attributed his narrow victory in November partly to his debate performance in September.

Americans wouldn't see another televised debate until 1976, when President Gerald Ford challenged Democratic candidate Jimmy Carter to a contest that became famous for a Ford blunder: The president was panned for quizzically declaring that the Soviet Union didn't dominate eastern Europe. Ford's mistake revealed another axiom of televised debates: one-liners matter. Subsequent debates would confirm that a single comment could define a candidate-for better or worse.

In the 1984 presidential debates, President Ronald Reagan cleverly squashed concerns over his age (compared with his younger Democratic opponent Walter Mondale) by quipping: "I am not going to exploit, for political purposes, my opponent's youth and inexperience."

When vice presidential candidate Sen. Dan Quayle loosely compared himself to Sen. John Kennedy in the 1988 debates, his opponent, Democratic Sen. Lloyd Bentsen, delivered a devastating comeback: "Senator, you're no Jack Kennedy." Quayle and Vice President George H.W. Bush easily won in November, but Quayle fought credibility questions for the next four years.

Other debates proved that subtle cues matter: President George H.W. Bush ignited a firestorm when he glanced at his watch during a debate with Democratic candidate Bill Clinton in 1992. Bush battled the perception that he was bored.

Vice President Al Gore's public perception suffered after a debate against George W. Bush in 2000 where Gore sighed loudly during Bush's remarks and aggressively stepped into his opponent's space. Campaigns took note: Manners matter too.

These days, campaigns spend months focusing on rehearsing a litany of possible questions with candidates, all while poring over the lessons of the past.

The ground rules

Debate organizers at the Commission on Presidential Debates have been planning this year's contests for nearly two years. The nonpartisan, nonprofit organization has managed general election presidential debates since 1987, determining the site and format for each contest.

Negotiating teams from each candidate's camp met to hammer out final details ahead of the debates. In mid-September, representatives from the Obama and McCain camps agreed to switch the topic of the first debate to foreign policy and national security, sending hosts at the University of Mississippi scrambling to adjust preparations. (Neither side revealed the reasons for the change, but both sides likely gained something they wanted in the deal.)

When the dust settled, so did the final schedule: The candidates would debate foreign policy and national security on Sept. 26 at Ole Miss in Oxford, Miss. The vice presidential candidates meet on Oct. 2 at Washington University in St. Louis to debate foreign and domestic topics. The second presidential debate comes in a town hall format on Oct. 7 at Belmont University in Nashville, and the final round takes place on Oct. 15 at Hofstra University in Hempstead, N.Y., where Obama and McCain will debate domestic issues.

Each debate will last 90 minutes (with no commercials) and feature a single moderator, who will introduce a question and allow each candidate to answer. The moderator will follow up over the next 10 minutes in a conversational style, allowing the candidates to interact with each other.

There's one formatting exception: the town hall debate. This event will feature a group of some 120 undecided voters enlisted by the Gallup Organization using telephone screening a few days before the debate. The participants will bring at least two questions they'd like to ask the candidates. The moderator will review the questions to cover the widest possible range of topics, but will not change the voters' wording.

With dozens of undecided voters asking virtually anything they want, this night promises to be one of the most revealing for viewers, and most challenging for candidates.

The referees

The enormous task of presiding over a fair fight falls to four lone moderators chosen by the commission.

Jim Lehrer, a 30-year veteran of television news and anchor of PBS' The NewsHour with Jim Lehrer, will host the first debate. Lehrer has been called "America's moderator" for good reason: During the last five presidential elections, the longtime journalist and author of 18 novels has moderated 10 of the nationally televised debates.

What makes Lehrer such a popular choice? "He gets out of the way," says Alan Schroeder, a journalism professor at Northeastern University in Boston. "You don't want a moderator who thinks the debate is about him."

Schroeder, author of Presidential Debates: 50 Years of High-Risk TV, told WORLD that well-informed, low-key moderators work best in general election debates when viewers need to focus on the candidates and the issues. He thinks the remaining three moderators are good picks: NBC's Tom Brokaw, Face the Nation host Bob Schieffer, and Washington Week host Gwen Ifill, who will moderate the vice presidential debates.

Schroeder says television journalists are logical choices because of their familiarity and ease with the medium: "For all these moderators-as well as for the candidates-these are the largest audiences they will ever face in their entire careers. You can't be nervous."

The contenders

When the cameras finally go live on debate night, it's hard to imagine the contenders won't fight nerves. For both McCain and Obama, the debates are the culmination of more than 18 months of relentless campaigning. For McCain, it's a pinnacle he's tried to reach for eight years.

Each candidate will have a different task: Obama will aim to convince voters he's experienced enough to handle the presidency and that McCain represents an extension of the Bush administration. McCain will aim to convince voters that his policy plans are different than Bush's and better than Obama's.

In order to succeed, both candidates will need to bring the same thing: mastery of the issues. With no low-brow campaign ads or accusatory press releases for at least 90 minutes, the debates will test the candidates' grasp of the issues and the validity of their proposals. "You can't fake it," says Schroeder.

Just days after the stock market took its deepest plunge since 9/11, viewers will listen for concrete answers to growing economic problems, and moderators will press candidates beyond their usual talking points on the economy and a range of issues. Schroeder says voters should pay attention to whether candidates are giving thoughtful answers: "I think it's a little disrespectful to the audience to just give the same old sound bites they've been giving all along."

Rosanna Perotti, chair of the political science department at Hofstra University, site of the final debate, told WORLD that viewers should also pay attention to how the candidates carry themselves for clues about their leadership skills: Are they thinking critically? Are they making good judgments? Do they handle pressure well? "Citizens are looking for someone who exhibits the qualities necessary to be a good president," she said.

On Oct. 7, viewers will apply those same questions to the vice presidential debates, a contest that may be watched by as many viewers as the presidential events. Though vice presidential debates have played a less significant role in the past, Palin's dark horse entry may draw more viewers than usual. (Her speech at the Republican National Convention drew more television viewers than Obama's address at the Democratic convention.)

Schroeder says viewers will tune in with one major question in mind: How will Palin perform? Given the governor's brief time in the national spotlight so far, predictions are difficult to make. "Maybe it's a smart strategy to save it all up for the debate," says Schroeder. "But it really puts a lot of pressure on her to come through with the goods on debate night."

Biden faces pressure, too, as he debates a woman who is highly popular within her party and beyond. George H.W. Bush faced criticism in 1984 for appearing to patronize Geraldine Ferraro in the vice presidential debates. "I don't think Biden is going to fall into the same trap, but he's still in fairly uncharted territory," says Schroeder.

As each of the four candidates faces a piece of uncharted territory in the final rounds of the elections, Perotti says she hopes viewers will rely on a well-worn path: "I hope people actually listen to what they're saying."

Debate milestones

1960

First-ever televised debates. Vice President Richard Nixon, recovering from a serious knee injury, looks pale and thin. Sen. John F. Kennedy looks fit and tan. Radio listeners declare Nixon winner. Television viewers favor Kennedy. Kennedy wins election by narrow margin.

1964

President Lyndon B. Johnson refuses to debate Republican candidate Barry Goldwater. Johnson easily wins election.

1976

President Gerald Ford debates Democratic candidate Jimmy Carter. Electrical power fails during live debate. The candidates stand on the Philadelphia stage in silence for 27 minutes.

1980

80.6 million viewers tune in for the Carter/Reagan debate. Most-viewed televised debate in history.

1984

Vice presidential candidate Geraldine Ferraro becomes first woman to participate in a general election debate.

1992

Independent candidate Ross Perot debates George H.W. Bush and Bill Clinton. Perot is the only third-party candidate ever allowed in nationally televised, general election debate.

2008

Sen. Barack Obama becomes first African American in a general election debate. Gov. Sarah Palin becomes second woman to participate.