Tokyo are the favourites to win the bid to become host city at the 125th IOC Session in Buenos Aires on September 7 with Istanbul also strongly fancied in what is their fifth attempt at trying to secure the Games.
Madrid meanwhile, who are bidding for the third successive time, are little more than outsiders due to Spain's poor economy as what began as a five-strong list gets set to be whittled down to one in less than eight months time.
Baku and Doha were cut from the list in Canada in May with Tokyo, Istanbul and Madrid's candidature files spanning several hundred pages in order to represent their plan for organising the Games.
The IOC's Evaluation Commission, led by Sir Craig Reedie, will visit all three cities for four days in March starting in Tokyo then Madrid and finally Istanbul before publishing a report in June with the 2020 Candidate City Seminar set for July.
Istanbul's bid has no more obstacles in its way after a decision to stage the 2020 European football championship across the continent lifted a huge burden, bid leader Hasan Arat said.
Arat, handing in his city's official bid book along with bid rivals Tokyo and Madrid to the International Olympic Committee in Lausanne, explained: "Nothing can really stop us."
Istanbul's bid had been dealt a significant blow last year when Turkey also bid to host Euro 2020 and the IOC said the country could not host both events in the same summer.
With UEFA unveiling plans for a continent-wide Euro 2020 in December, Istanbul saw its Olympic chances restored.
"When that question came up we always said that our national priority was Istanbul 2020," Arat told Reuters in a telephone interview from Lausanne.
"This (Euro 2020) case is closed for us now. I hope that people now understand more that the priority is the Games. (Turkey Prime Minister) Tayyip Erdogan said (during the 2012 London Games) 'the Olympic flame is in my heart but now I want to hold it'. That is a top commitment.
"Nothing can really stop us. We promised our people that we will do our work very good," he said.
The IOC did not want an Olympic host nation holding another major event in the same year as the Games due to potential preparation problems and sponsor issues that could arise.
It had warned Turkey it would need to drop its Euro bid if Istanbul, bidding for the fifth time in the last six votes, was awarded the Games next year.
"It is a new bid for a new Turkey," Arat said as the Turkish metropolis looks to become the first city in a Muslim nation to hold the world's biggest multi-sports event after a string of failed attempts.
"The economic situation is not the same as in the previous bids. When you look at the average economic growth it is 5.2 percent annually between 2002 and 2011," Arat said.
"There is political stability, government backing is very important and there is big support from the international sports events. That makes us very strong," he said.
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