Friday's vote by the International Olympic Committee in Copenhagen to select the host city for the 2016 Summer Games is too close to call.

Any of the four candidate cities — Chicago, Madrid, Rio de Janeiro and Tokyo — could win. Then again, any city could go out in the first round of the secret ballot.

For each city, here are three reasons they could win and three reasons they could lose:

CHICAGO

Why Win:

1. The Obama factor: First lady Michelle Obama works her charm in lobbying individual IOC members, then President Barack Obama flies in for Friday's final presentation. The Obamas explain their deep roots with the Windy City and how their Chicago home sits just a few blocks from the planned venue for the 2016 opening ceremonies. Just swinging two or three votes could make the difference.

2. Lake Michigan: The city's venue plans are laid out along Chicago's picturesque downtown waterfront, with venues only a short distance from the athletes' village.

3. Low risk: The Summer Olympics haven't been held in the United States since 1996, and the IOC knows the games would be in safe hands if they returned to America. The IOC also would have a secure source of TV and marketing income.

Why Lose:

1. Rio's romance: Chicago lacks the emotional, geographical and sentimental pull of Rio de Janeiro, which has impressed IOC members with its pitch for taking the Olympics to South America for the first time.

2. USOC baggage: Some members of the European-dominated IOC remain bitter over long-standing disputes with the U.S. Olympic Committee over its extra share of TV and marketing revenues. The USOC also ruffled IOC feathers recently by announcing the launch of its own TV network. The project has since been put on hold. U.S. influence inside the IOC has sharply diminished, with no American member even on the executive board.

3. Lesser known: Many IOC members have never been to Chicago and are more familiar with the three other cities. Since the Salt Lake City bid scandal, members are barred from visiting candidate cities, so many will vote based only on what they have read and heard about Chicago.

MADRID

Why Win:

1. Readiness: Madrid, which also bid for the 2012 Olympics, says 77 percent of its venues are ready or under construction. That means the IOC won't have to worry about the city being ready on time or huge sums of money being needed for new facilities.

2. Experience and reputation: Madrid has hosted countless top sporting events and is familiar to many IOC members. It enjoys a reputation as a fun-loving, vibrant city.

3. Samaranch factor: Former IOC president Juan Antonio Samaranch is nearly 90 but still has influence with some members and could swing a few crucial votes in Madrid's favor.

Why Lose:

1. Geography: The 2012 Olympics will be in London; the 2014 Winter Games in Sochi, Russia. The IOC might hesitate to take the games to Europe again in 2016, even though Madrid has been portraying itself as the "Hispanic candidate" to distance itself from the European tag.

2. Rio rivalry: Madrid is competing with Rio for Latin American votes. The tension spilled out when Spanish Olympic Committee vice president Jose Maria Odriozola reportedly ranted that Rio was "the worst" of the four candidates, prompting an ethics complaint from the Brazilians.

3. No Obama figure: King Juan Carlos, a former Olympic sailor, is in Copenhagen to provide high-profile royal support, but he lacks the star power of the new American president and his wife.

RIO DE JANEIRO

Why Win:

1. Geography: Along with Africa, South America is the only continent never to have hosted the Olympics. Rio has made a strong case that the time has finally come to take the games to a new region. That's by far the strongest emotional and sentimental argument of the race.

2. Lula: Barack Obama isn't the only president using his considerable influence to win the games. Brazil's charismatic Luiz Inacio Lula da Silva has been on the campaign trail nonstop for Rio and is in Copenhagen. The bearded former union leader insists Rio, Brazil and South America "need" the games, an argument the other three cities can't make.

3. The setting: Rio has the beaches, the beauty and the backdrop for a visually stunning Olympics, an ideal venue for television broadcasts. What's more fitting than beach volleyball on the Copacabana?

Why Lose:

1. Infrastructure: Rio will have the most preparation work to do of all the four cities if it gets the games. Its budget of $14.4 billion is way higher than the others. Its venues are more spread out, requiring transportation improvements. That leaves an element of potential risk and uncertainty, especially with Brazil also facing the challenge of hosting the 2014 World Cup.

2. Perceived arrogance: Some IOC members might be getting sick and tired of being told that it is their duty to send the games to Brazil.

3. Crime: Rio has a higher murder and crime rate compared to the other cities, meaning security would be a constant issue.

TOKYO

Why win:

1. Underdog factor: Tokyo has been much more understated than its bid rivals but could pull a surprise and sneak through when the others cancel themselves out.

2. Legacy: Tokyo, which hosted the Olympics in 1964, would use some facilities upgraded from those games, along with new venues to create a 50-year legacy.

3. Venue plans: Tokyo has a very compact bid with a strong focus on environmental sustainability.

Why Lose:

1. Beijing: IOC members are reluctant to return to Asia so soon after last year's Beijing Olympics.

2. 1964: Tokyo has held the games before, while the other cities are still trying to get their first.

3. Lack of buzz: The Japanese haven't been able to generate enough passion and excitement behind the bid to convince IOC members they really want or need the games.