In a keynote address at McCormick Place, Louis Farrakhan called Obama "the hope of the entire world that America can change," WLS-TV, Chicago, reported.
Farrakhan says he is not telling anyone what way to vote but said Obama's background could make him just the leader the United States needs.
"A black man with a white mother may be what could lift America from her fall," Farrakhan told the Nation of Islam's annual Savior's Day event Sunday.
Farrakhan gave up his leadership role with the Nation of Islam due to health problems resulting from his battle with prostate cancer.
WLS said 20,000 people attended Sunday's event.