Barack Obama launched an emotional appeal to the International Olympic Committee to choose his home city Chicago to host the 2016 Games.

Chicago and Rio de Janeiro are viewed as favourites to win the contest ahead of Madrid and Tokyo.

The US president flew into Copenhagen this morning in time to speak at Chicago's final presentation to the IOC ahead of the vote at 5.30pm this afternoon.

Obama told the 106 IOC members: "I urge you to choose Chicago, I urge you to choose America.

"If you do, if we walk this path together, then I promise you this, the city of Chicago and the United States of America will make the world proud."

His wife Michelle Obama, also from Chicago, spoke at the presentation about her late father who suffered from multiple sclerosis.

"He showed me how to throw a ball and a mean right hook better than any boy in the neighbourhood," she said.

London's successor as host city of the summer Olympics has been rated as one of the closest of all time.

London 2012 chairman Sebastian Coe said: "Any one of these four cities could deliver a great Olympics - this is probably the highest quality contest there has been.

"It is very close competition and it could all be decided by the final presentations."

Rio's presentation appealed to the IOC to give the Olympics to South America for the first time.

Brazil's President Lula said: "It is time to address this imbalance and to send a powerful message to the whole world: the Olympic Games to all peoples, to all continents, to all mankind.

"For South America, it will be a magical moment. For the Olympic Movement, it will be an opportunity to feel the warmth of our people, the exuberance of our culture, the sun of our joy."

Rio also stressed they have the strongest of financial guarantees from the government.

Tokyo's bid was presented by Japanese prime minister Yukio Hatoyama who also stressed financial guarantees.

He said: "Let us welcome you all to Tokyo in 2016 to savour the magic of the Olympic Games".

Tokyo claimed theirs would be the most environmentally-friendly Games, and the best for athletes.