The Olympic dreams of London, Paris, Madrid, New York and Moscow rest in the hands of the 116-strong International Olympic Committee on Wednesday.
So who makes up this diverse bunch of royals, politicians, sports administrators and former Olympians?
Find out with our rundown on the members from South America. Check out another region by clicking on the map above.
Three of the 116 will not vote at all, while another 14 cannot vote in the first round, for a variety of reasons.
Carlos Arthur Nuzman Brazil
Key player: Joao Havelange
Age: 63 - member since 2000
Lawyer. Member of Brazil volleyball team at 1964 Tokyo Olympics. Member of the Court of Arbitration for Sport.
Ivan Dibos Peru
Age: 66 - member since 1982
Former Mayor of Lima and Peru rowing champion.
Joao Havelange Brazil
Age: 89 - member since 1963
Oldest and joint longest-serving member. Former Fifa president. Olympic swimmer (1936) and water polo player (1952).
Julio Cesar Maglione Uruguay
Age: 69 - member since 1996
A national swimming champion and former head of the Uruguayan Soccer Association.
Fidel Mendoza Carrasquilla Colombia
Age: 79 - member since 1988
Colombian air force physician. Former Colombian Olympic Committee president.
Antonio Rodriguez Argentina
Age: 79 - member since 1990
Colonel in Argentina army. Competed in modern pentathlon at 1948 Olympics in London.