To those saying that all the GOP needs to do is win back the collar counties, you are sorely mistaken. In 2010, the Tea Party year, Brady swept the collar counties, but still lost. It was close, but he couldn't get the victory despite effectively winning everything but Cook County. It takes a lot to get this state to flip.
Didn't Quin win with (nearly) just Cook county alone? I mean his vote margin total from the 2-3 other counties he won was just in the hundreds or maybe a thousand or two.
It is quite possible for a Democratic presidential candidate to win Illinois winning just Cook county, isn't it?