Rep. Rahm Emanuel, D-Ill., left, and others, applaud Democratic presidential candidate Sen. Barack Obama, D-Ill., Friday, June 6, 2008, during an unscheduled stop at the Chicago 2016 Olympic Rally in Chicago. (AP Photo/Charles Rex Arbogast)
Presumptive Democratic presidential nominee Senator Barack Obama (D-IL) pauses during a Chicago 2016 Olympics rally in Chicago June 6, 2008. REUTERS/John Gress
Presumptive Democratic nominee Sen. Barack Obama, D-Ill., right, smiles as he listens to U.S. Rep. Rahm Emanuel, D-Ill., during an unscheduled stop at the Chicago Sister Cities International Rally in Chicago, Friday, June 6, 2008. (AP Photo/Charles Rex Arbogast)
Rep. Rahm Emanuel, D-Ill., left, huddles with Democratic presidential candidate Sen. Barack Obama, D-Ill., right, Friday, June 6, 2008, during an unscheduled stop at the Olympic rally in Chicago. (AP Photo/Charles Rex Arbogast)
Rep. Rahm Emanuel, D-Ill., left, and others, applaud Democratic presidential candidate Sen. Barack Obama, D-Ill., Friday, June 6, 2008, during an unscheduled stop at the Chicago 2016 Olympic Rally in Chicago. (AP Photo/Charles Rex Arbogast)
Democratic presidential candidate Sen. Barack Obama D-Ill., jogs onto the stage at a Chicago 2016 Olympic rally at Daley Plaza in Chicago on Friday, June 6, 2008. (AP Photo/Alex Brandon)
Democratic presidential candidate Sen. Barack Obama D-Ill., speaks at a Chicago 2016 Olympic rally at Daley Plaza in Chicago Friday, June 6, 2008. (AP Photo/Alex Brandon)
Presumptive Democratic presidential nominee Senator Barack Obama (D-IL) (R) shakes hands with Mayor Richard M. Daley during a Chicago 2016 Olympics rally in Chicago June 6, 2008. REUTERS/John Gress
Democratic presidential candidate Sen. Barack Obama D-Ill., second from right, flanked by Olympic athlete Jackie Joyner-Kersee, left, and Maggie Daley, wife of Chicago Mayor Richard M. Daley, right, applaud at a Chicago 2016 Olympic rally, Friday, June 6, 2008, at the Daley Center Plaza in Chicago. (AP Photo/Alex Brandon)
Presumptive Democratic nominee Sen. Barack Obama, D-Ill., left, hugs Olympic Gold Medalist Jackie Joyner-Kersee, right, during an unscheduled stop at the Chicago 2016 Olympic Rally in Chicago, Friday, June 6, 2008. (AP Photo/Charles Rex Arbogast)