You point to a pattern I’ve noticed in elections in recent years. Dems seem to have the advantage in presidential election years when voter turnout is much larger. In midterm elections, the electorate tends to be smaller, more disciplined, older, whiter, more conservative, and therefore more Republican than is generally the case in presidential election years.
James Carville was famous for coining the phrase, “it’s the economy, stupid.”
Now days I think it “it’s the demographics, stupid”.
And then in IL the GOP has the added difficult of having to deal with Cook County, easily the most corrupt county in the nation where cemeteries have precinct captains and ward heelers.
That pattern appears to be nationwide, and nobody has capitalized on that pattern more than Scott Walker. He won two elections in non-presidential election years and in both cases the turnout was about 2.3 million. He won his recall with a voter turnout of about 2.5 million. In the 2012 election the voter turnout was over 3 million and Obama took Wisconsin by 8 percentage points with Paul Ryan on the ticket. Nothing seems to bring the Dems out like a presidential race, and if Scott Walker is the nominee there is no guarantee he'll carry his home state.