Interesting. This seat could determine which party controls the new Senate.
And remember, that if Hillary becomes president, then the Democrats take control of the Senate if the new Senate is a 50-50 tie between Dems and Republicans, due to Tim Kaine as VP being the tie breaking vote.
I read Illinois senate is lost for GOP , Wisconsin as well and now PA & NH are tough to keep. ( One of many sites rating Senate races http://www.electionprojection.com/senate-elections.php )