It's that time again. Four years after London was awarded the 2012 Olympics, the members of the International Olympic Committee meet later this week in Copenhagen to decide where the 2016 Games will be held. The contenders are Chicago, Madrid, Rio and Tokyo. It's another strong field, and appears evenly matched. Or at least it did, until Chicago played what it hopes will be its trump card, President Obama. He's agreed to go to Denmark to personally support Chicago's bid.
The process of deciding which city gets to host the Olympics is still pretty mysterious, with the voting almost as secretive as a Papal conclave. The different cities don't really bid for the Games in the traditional sense anymore, the whole process is far more like a campaign, with all the tools of spin and PR familiar from the world of politics. And this is where politicians themselves come in.
The people trying to win the Games for each city don't really know which part of their campaign could make the difference. Will it be the technical specifications of the venues? The success of the IOC members' visit to the city? How about the transport links? Any of these might prove crucial, after all, in 2005 London only defeated Paris by a mere three votes.
But if there is one aspect to modern Olympic bids that everyone seems to agree is significant, it's the personal support of political leaders. Tony Blair put his weight firmly behind London four years ago, and more recently Vladimir Putin did the same for Sochi's successful Winter Olympics bid. Although the bitter rows about healthcare and other policies may have taken some of the shine off Mr Obama's image in the US, he remains hugely popular internationally, and the Chicago bid team will hope his gladhanding of IOC members in Copenhagen seals the deal for them. If Chicago wins, it'll be Obama wot won it.