Candidates were allowed to begin filing with the Illinois State Board of Elections Thursday for a Feb. 26 Democratic primary, the Chicago Sun-Times reported.
The winner will be favored to win an April 9 special election in the heavily Democratic district, observers said.
Among those who filed petitions were Chicago Alderman Anthony Beale, State Rep. Toi Hutchinson of Olympia Fields, State Senator-elect Napoleon Harris of Flossmoor and former Congressman Mel Reynolds, of Dolton, who was replaced by Jackson.
More people are expected to file before the Jan. 7 deadline, the Sun-Times report said.
Jackson, a Democrat, resigned Nov. 21 while undergoing health treatment amid a federal investigation over his use campaign funds, the Sun-Times said.