New York declared it would win but Paris remained the marginal favourite on Wednesday as the International Olympic Committee (IOC) opened an all-day meeting to decide the host of the 2012 Summer Olympics.
London, Madrid and Moscow are also campaigning for what many see as the richest prize in sport. The decision, after a vote by all IOC members at the Raffles City Convention Centre, will be announced by president Jacques Rogge at around 1715 IST.
It is the first time five of the world's most prominent cities have competed for the right to stage the Games and the campaign has been the most fiercely contested in Olympic history.
New York tried to land a late psychological blow by declaring it would win just hours before IOC members gathered at 0600 IST.
New York bid chief and deputy mayor Dan Doctoroff issued a bullish statement which read: "New York's bid is perfectly positioned to win the 2012 Games. This evening New York's Olympic dream will become reality."
But Tuesday night gossip in the luxury hotels of the Raffles City complex suggested Paris remained marginal favourites, ahead of London, Madrid, New York and Moscow.
Doctoroff apart, it was almost impossible to find anyone prepared to stick his or her neck out and confidently declare a winner.
French President Jacques Chirac and British Prime Minister Tony Blair, who have both been in Singapore to promote the Paris and London bids respectively, met at a party on Tuesday night after the formal opening of the four-day IOC session.
The two leaders, momentarily at least, buried their differences and shook hands amicably.
Blair, who spent two days in Singapore trying to woo IOC members to the London cause, then flew back home to host the G8 summit in Gleneagles, Scotland.
Chirac will join him there after taking part in the Paris presentation before the IOC.
Paris goes first, followed by New York, Moscow, London and Madrid. An evaluation commission, which examined the five bids in miniscule detail, then presents its report to the IOC.
The commission rated Paris and London's bids as of "very high quality" with Madrid and New York assessed as of "high quality".
Voting is due to start at 1515 IST. Unless one candidate gains an absolute majority of votes, the lowest ranked city drops out and a new round of voting is made.
This continues until a winner emerges.
Rogge will announce the victorious candidate during a televised ceremony at 1700 IST.
The IOC has 116 members of which 114 were expected in Singapore.
Members from countries with candidates are ineligible to vote while their cities are in contention. This means 99 members can vote in the first round.