“Bridge together” and “Discover tomorrow” are Istanbul's and Tokyo's respective official slogans. But it may not be the slogans or the cities' prominent supporters that count when the host city is selected in a secret ballot at the IOC meeting in Buenos Aires on September 7.

The committee accepted three candidatures - including that of Madrid, which was already voted out - in May 2012, after eliminating Doha and Baku from the race. The IOC then graded the applicants through official selection and evaluation criteria, awarding 8.02 points to Madrid, 8.02 to Tokyo and 6.98 to Istanbul.

In its Evaluation Commission Report in June 2013 the IOC praised all three candidate cities for their “high quality” applications and stated that they were all in a position to stage successful games.

The report grades each application according to the 14 IOC criteria. One of them is “Vision, Concept and Legacy”, where Istanbul, for example, has stressed that it based its concept on its geographic location as a bridge between Europe and Asia. Tokyo vows to “reinforce Olympic values” and “promote national spirit, unity and confidence, in particular following the March 2011 Great East Japan Earthquake and tsunami.”

The cities in the running claim to have their populations' broad support for the candidacy. But there is opposition too: Critics of the Olympic bid are warning of possible negative side effects of the games ranging from rising rents to environmental damage.

Infrastructure is one of the most controversial topics. Tokyo's subway system is notorious for being dramatically overcrowded, and the $9.8 billion (6.3 billion euros) Istanbul wants to invest into public transport and road construction may not even be enough.

Another contentious topic is anti-doping measures. Spain had been in the headlines for its dramatic doping cases culminating in the trial of Eufemiano Fuentes and his long-running high-profile doping scheme, which was behind the rise and fall of former star cyclist Lance Armstrong, the seven times Tour de France winner, who had all his titles revoked. Observers are wondering whether Spanish authorities can be trusted to ensure clean games, or whether Turkey has the more convincing strategy here, seeing as they recently banned 30 athletes for doping.

Some IOC critics say that in the end deciding on a host city may not be based on the individual applications, but rather on the principle of regional rotation, making it unlikely for two consecutive Games to be staged on the same continent. And that again may lead candidates to think strategically with their own chances in mind, should they want to place bids for future events. Sheikh Al Sabah of Kuwait, for example, may think twice about supporting Tokyo or Istanbul, if their victory would diminish Doha's chances for 2024 or 2028.

Several changes have been made since the 2002 Winter Olympic Games were controversially awarded to Salt Lake City, which had allegedly bribed IOC delegates, leading to several expulsions. In an attempt to prevent possible corruption allegations, Istanbul was asked to remove from its application the pledge to set up a special fund to the tune of $250 million for the IOC and International Paralympics Committee (IPC). Likewise Tokyo was not allowed to campaign on free transport for all National Olympic Committee members.

Other initiatives are beyond IOC control: When Japanese Premier Shinzo Abe attended a meeting with African heads of government in June this year, he asked for their support for Tokyo's bid – and casually mentioned that his government was intending a $25 billion development package for Africa.

During the final presentation of the bids in August in Lausanne, Switzerland general opinion was that Madrid had improved its chances, also because things had begun to look up again for their economy.

Hot topics like Istanbul's heavy handed crackdown on protestors in the city's Gezi Park earlier this year, or recent alarming reports of rising radiation levels around Japan's Fukushima power plant were not mentioned in Lausanne. The reasoning is that such issues may well have been sorted out by the time the Games take place. After all, the delegates are to decide on an event that is to take place in seven years' time - in 2020.

The decision will be announced in Buenos Aires on Saturday at 20UTC www.dw.de/news