From Unlikely Voter: The Illinois Senate race is already set to be an ugly war, only distinguished from France 1916 by the lack of chemical warfare. Both candidates are hated and have baggage that is not going to go away. Either one can win, though, judging by the polling I've seen.
Maybe Quinn is doing badly because Blago is back in the news, but this is just bad. Brady leads 48-35 (MoE 4), and Quinn is down to a negligible 6% chance of leading according to this poll. This is the kind of poll that makes people stop caring about a race, in my personal experience seeing such polls the other way in elections past in California.
And of course, every Democrat who stays home, or likewise for any independent who leans toward the Democrats, is a vote lost to the Senate race. It won't matter for the Governor, but in a close Senate race, such voter depression could be critical.
Because even more so than Russ Feingold, Alexi Giannoulias needs every excited voter he can muster.