US President Barack Obama's decision to travel to Copenhagen to support Chicago's bid to host the 2016 Olympics shows not only how close the race is but also how edgy the city is about its chances.
President Obama initially said he wouldn't be part of the delegation but with Chicago facing stiff opposition from Madrid, Rio de Janeiro and Tokyo he's changed his mind.
The impact of star personalities on Olympic bids has been demonstrated when lobbying by former Britain Prime Minister Tony Blair helped London win the 2012 Games, and Russian President Vladimir Putin led Sochi's bid for the 2014 Winter Games.
