So why are Senate Majority Leader Harry Reid (D., Nev.) and his fellow Senate Democrats making the Kochs the centerpiece of their midterm efforts and not Mr. McConnell, who is hardly a sympathetic political figure himself?

Two reasons: 1) Democratic donors certainly know all about the Kochs and their political spending, and 2) You have to have somebody to run against – and many Democrats believe the Kochs are as good a bogeyman as Mr. Reid will get. There’s no Mitt Romney and his Bain Capital connections this time around, but Democrats hope the Kochs provide a suitable stand-in for what they are billing as Republicans’ allegiance to big businesses and special interests.