Istanbul, Turkey -- Chicago and three other cities vying for the 2016 Summer Games will make their case today to the regional group with the most votes in the Olympic movement.

Tokyo, Madrid and Rio de Janeiro also will make presentations to the general assembly of the European Olympic Committees, which represents 50 countries and holds the balance of power in the Olympics.

A video message from President-elect Barack Obama, taped since his election victory, is expected to be included in Chicago's 20-minute pitch. Obama, who lives in Chicago, delivered his acceptance speech before a huge crowd in Grant Park, a centerpiece of the city's Olympic bid.

The audience of 500 delegates is expected to include between 20 and 25 voting members of the International Olympic Committee, EOC president Patrick Hickey said.

The full IOC will select the host city in a secret ballot on Oct. 2 in Copenhagen, Denmark. But the campaign is already in full swing as the cities prepare to submit their final bid documents to the IOC in February.