A gunman fired three shots at a candidate for the City Council on Sunday night, two days after an unexploded bomb was found outside his campaign headquarters, police said.
Manuel A. Torres, who is seeking the council seat from the 26th Ward in Tuesday's election, was not injured, police said.
"It's almost like whoever stays alive is going to be the next alderman up here," Patrolman Raymond Heyn said.
Police said Sunday night that no arrests had been made.
Political infighting has been bitter in the ward, one of seven in which special elections will be held Tuesday. Boundaries of the affected wards were redrawn under a court order aimed at correcting past racial gerrymandering.
In addition to increased police patrols around campaign headquarters, federal marshals were asked to monitor the special elections after concerns were raised about possible vote fraud.
Mayor Harold Washington, who leads a 21-member minority bloc, needs only four more votes to take control of the 50-member City Council, because he would cast the deciding vote in case of a tie. A 29-member majority bloc, led by Alderman Edward R. Vrdolyak, has played adversary to many of Washington's programs.
Torres has been endorsed by the Vrdolyak faction, while his opponent, Luis V. Gutierrez, is backed by Washington.