A special election will be held in the coming months, according to state law.
It turns out that the "endorsement" Rev. Jackson reportedly gave to Lt. Gov. Stratton before he passed away, that she released over the weekend, was not actually an endorsement.
Just days before the primary, Lt. Gov. Juliana Stratton announced that Rev. Jesse Jackson endorsed her before he died, stirring some last-minute campaign controversy.
Super PACs are spending millions on this race.
ABC7 caught up with the two frontrunners on Thursday as they work to rally supporters to the polls.
Illinois Governor JB Pritzker contributed $5 million dollars to a super PAC supporting his Lt. Governor Juliana Stratton, according to FEC records. She's one of multiple Democrats running for the U.S. Senate seat being vacated by Dick Durbin.