Pritzker is not going to reach Obama 2012/Clinton 2016/Duckworth 2016 margin of victory levels.
His ceiling is probably at the Durbin 2014/Kerry 2004 margin of victory level, honestly.
Not sure why that is - Rauner is remarkably, shockingly unpopular. His approval ratings are very low and he seems to be trailing by 15 points in polls regularly. GOP enthusiasm is just not there for Rauner.
I'm not saying Pritzker is going to win big because I like Pritzker, but because Rauner is one of the worst GOP governors in the country and the GOP is largely abandoning him.