They could but I don't see him making any headway. Too many Democrats in Chicago and upstate.
People keep thinking "downstate" is Republican, but is that true? Wasn't the late Adlai E. Stevenson, II, from downstate -- Libertyville? Stevenson lost IL twice though in 1952 and 1956. And isn't Springfield more Democrat than not? The district next to the Ohio River was represented for years by the popular late liberal Paul Simon. I don't think "downstate" is much Republican any more. It seemed like IL went even more Democrat after it retired Moseley-Braun. Fitzgerald never seemed even to try to be a decent senator; maybe he knew that he could not win again, no matter how well he performed.