The choice of host city for the 2020 Olympics is still 15 months away, but a shortlist is due to be announced on Wednesday from declared candidates Baku, Doha, Istanbul, Tokyo and Madrid. The International Olympic Committee (IOC) at this early stage in the competition only looks at the cities\' abilities to host a major sporting event, ranking their transportation and other infrastructure and the challenges they face to ramp up in time for the event. Tokyo are the only one of the candidates to have hosted the event and seen widely as the early front runners, while Istanbul were seen as the dark horses until a spanner was thrown into the works when Turkey also announced they were bidding for the 2020 European football championship. IOC President Jacques Rogge told AFP in an interview earlier this month that IOC rules state that a Games host country cannot hold another major sports event in the same year. \"Initially they will be judged on their technical capacity on May 23 in Quebec City,\" said the 70-year-old Belgian. \"In other words their potential to host the Games. \"On September 7 next year in Buenos Aires, if Istanbul is elected we will respectfully ask them not to host the European Championships. \"Ultimately, it will be for the government (in Ankara) to make their mind up but I would say the election would be conditional on not organising another competition.\" Of the other candidates Doha failed to even make the short list last time and the subsequent furore after Qatar was awarded the 2022 World Cup has according to some made IOC members reluctant to suffer the same press as FIFA did. Baku also failed to make the short list last time but say they have learnt from their mistakes this time round. \"This is an excellent bid, really carefully prepared to avoid the mistakes on the previous bid,\" Sports Minister Azad Rahimov told AFP on Tuesday. \"The country has changed a lot in the last four years. It is a new country and a new approach,\" added the 47-year-old. Ordinarily Madrid would be seen as running Tokyo close as they beat them in the race for 2016 and finished runners-up to Rio de Janeiro - but the spectre of the abortive Rome bid and their own dire financial crisis hangs over them. Considered a favourite at its launch in 2010, and described by the Rome bid\'s chairman Mario Pescante as serving as \"a blueprint for a return to fiscal responsibility and real sustainability in the Olympic bidding process,\" the city withdrew on the eve of the deadline for candidates to declare themselve. A lack of support from an Italian government preoccupied with the euro zone debt crisis was the main factor. Their withdrawal added to growing criticisms that the Games have become too expensive for most cities of the world to host. However, unlike their Italian counterparts the Spanish Government is unlikely to force them to withdraw and with a new low-cost bid Madrid is expected to go through to the next round despite Spain\'s deep economic woes. It is to many peoples eyes though Tokyo that remain the pacesetters. They have a sound plan for hosting the Games while IOC members have noted the perseverance of the Japanese people in the wake of last year\'s tsunami and Fukushima nuclear meltdown to press ahead with their Olympic bid, despite the tragedy. Once the shortlist is announced, the candidates will have 15 months to persuade delegates to vote for their respective bids. But as Rio de Janeiro proved when it came from behind to win the right to host the 2016 Games, none of the candidates can be considered a shoo-in.