BUENOS AIRES — From the Fukushima nuclear leak to the war in Syria to Europe’s economic crisis, the choice of the host city for the 2020 Olympics is fraught with risks.
Picking the site with the least risks shapes up as the challenge for the International Olympic Committee on Saturday in a tight three-city contest that members say is too close to call.
‘‘It’s certainly an open race,’’ South African IOC member Sam Ramsamy said Friday. ‘‘They all have positive and negative points. The final presentations will be crucial.’’
After a two-year global race, Tokyo, Madrid, and Istanbul spent their final full day of campaigning Friday to drum up last-minute support in their bid to secure the biggest sports event on the international stage.
Tokyo has been seen as a slight favorite, but its status has been put into question by concerns over the leak of radioactive water from the crippled Fukushima plant.
Madrid, once counted out because of Spain’s financial troubles, has generated the most recent buzz and could be poised for an upset win.
Istanbul, dogged by the war in neighboring Syria and possible Western military strikes against the Assad regime, looks to be the outsider.
London bookmakers have been taking a rush of bets on Madrid, whose odds have been slashed from 4-1 a week ago to 5-4. Tokyo remains the favorite, though its odds have shortened to 5-6. Istanbul is 6-1.
IOC elections are extremely unpredictable as members vote by secret ballot and take different personal reasons into account. Some members are still undecided and will be waiting for the final 45-minute presentations before making up their mind.
Leading the delegations will be the prime ministers of all three countries. Shinzo Abe of Japan, Mariano Rajoy of Spain, and Recep Tayyip Erdogan of Turkey were all flying to Buenos Aires straight from the G20 summit in St. Petersburg, Russia.
If all IOC members are in attendance, 97 will vote in the first round. With a majority required for victory, the process is likely to go two rounds. The city with the fewest votes is eliminated after the first round, setting up a final head-to-head ballot.