With only hours to go before the International Olympic Committee votes today, the two cities are believed to have drawn away from their rivals Madrid, Moscow and New York in the campaign to stage the world's biggest sports event. After three days of intensive lobbying of voters around the IOC general assembly, estimates put the winning margin at single figures for either city, each of which would make history by becoming the first to stage three Games since the start of the modern Olympics.
Jacques Rogge, the IOC president, predicted that the outcome could be as close as the two-vote margin which gave Sydney the 2000 Games over Beijing. He even raised the prospect of a tie, in which case he would have the casting vote.
The two frontrunners have chosen different approaches. The more conservative approach of Paris has promoted as virtues its existing facilities and expertise in staging major sporting events. The London bid has been more aggressively marketed, especially Britain's passion for sport and the "legacy" factor that would bring regeneration to the proposed site in Stratford, East London.
Madrid, despite gaining ground due to the influence of the former IOC president Juan Antonio Samaranch, is thought to still be behind the two frontrunners, with Moscow and New York rated as outsiders.
London and Paris were confident that they had established a bedrock of support to survive the first round of voting when many of the 115 voting members cast sympathy ballots.
Many members arrived in Singapore expecting that Paris would be confirmed as the favourite. But a late surge by London is thought to have come thanks largely to lobbying by Tony Blair. The Prime Minister, who will be hosting the G8 summit in Edinburgh when the vote is announced at 12.46pm BST today, has aimed to secure backing in a series of private meetings.
As well as targeting the Latin American vote, he is thought to have brokered a deal with the Italian leader, Silvio Berlusconi, to minimise the influence of the pro-Paris IOC member Mario Pescante, who is thought to command a number of votes in Europe.
Blair said: "A love of sport, a belief in the ability of sport to bring people together, to educate, to enhance people's lives and a complete determination if we are fortunate enough to host the Olympic Games - we believe in something that doesn't just last for the few weeks of the Games but lasts for the generation to come.
"That's our passion. That's why we want the Games so much, that's why we believe we can deliver something not just for our own country but for the Olympic movement," the Prime Minister said.
The 2012 race is considered still open in the absence of defining issues that have driven previous elections. But this race offers an unprecedented field of world-class cities, all capable of hosting good Games, and none has a built-in sentimental advantage.
"Before, we have known more or less which one we think should win and try to move it in the right direction," the IOC executive board member, Gerhard Heiberg of Norway, said. "This time it's not necessary. It's very open."Reuse content