The White House says President Barack Obama will personally lobby for the city of Chicago to host the 2016 Olympic Games.
Mr Obama is to travel to Copenhagen on Friday to support the bid at a meeting of the International Olympic Committee. Mrs Obama, will also attend.
Chicago faces opposition from Madrid, Rio de Janeiro and Tokyo in the vote. It was chosen ahead of four other US cities to bid for the Games.
King Juan Carlos of Spain, Brazil's president and Japan's new Prime Minister will also attend the IOC meeting.
Each of the cities will make a presentation on Friday to the IOC's 115 members, who will cast their votes the same day.
President Luiz Inacio Lula da Silva expressed hope on Monday that he would "return from Copenhagen with a victory" for Brazil.
The BBC reports Rio de Janeiro successful staged the Pan-American Games in 2007 and is to host the 2014 World Cup.