Yes, it’s a bad sign that a Democrat won in a district that gave George W. Bush 55% of the vote in 2004. But before we get too carried away, keep in mind that the Republican Party is weaker in Illinois than it’s been in decades thanks to the Ryan-era horror-show. Jim Oberweis was by all accounts a terrible candidate. I’m guessing the GOP is doing somewhat better at candidate-recruitment elsewhere (though I haven’t done a systematic survey).
