The city picked to host the 2016 summer Olympics will win the vote by a tiny margin, International Olympic Committee president Jacques Rogge predicted yesterday.

Chicago, Tokyo, Rio de Janeiro and Madrid are bidding to host the 2016 Games with the IOC voting on the best bid on October 2 at its session in Copenhagen.

"It is probably going to be a couple of votes," Rogge said of the winning margin in a teleconference.

"Two, three four votes... it is going to be very close. Don't forget that something like four, five votes is a change of mind of just two or three people.

"Maybe the (cities') last presentation (in Copenhagen) will sway the votes of two members," he said.

There are currently 115 IOC members.

Unlike on previous occasions, no clear frontrunner has emerged after two years of campaigning, with all four bids scoring well on an IOC evaluation report this month.

"We are heading for what I believe will be a fascinating 10 days in Copenhagen," said Rogge. "We are very thrilled that the four candidates are of first class. Each of them could organise very good Games."

Rogge said IOC members would consider all aspects including potential revenues and geographic location - Rio is bidding to be the first South American host city - but ultimately the decision would be taken on the Games "fundamentals".

"The vast majority of members will vote on the fundaments," he said.

"Is it a good bid, do we trust the people in charge, is transport ok, are the venues ok... these are the most important considerations."

"It is the confidence you have in the people who have made the bid and will organise the Games."

He added that Olympics were not awarded to anonymous organising committees but to those running the bids.

"You give the Games to a couple of people and the charisma of those people," he said.

"Revenue is not the main and most important factor."