In the Illinois race, Dillard not only received money and support from some Democrats, but he also earned the endorsement of one big union. “My advice is that, if you are a suburban or downstate Democrat or independent and you care about public education, you should vote in the Republican primary for Kirk Dillard,” Illinois Education Association president Cindy Klickna told union members. The union also sent pamphlets to its members urging them to support Dillard. Almost twice as many votes were cast in the Republican primary this year than the Democratic one — though Democratic incumbent Pat Quinn was essentially unopposed, the healthier GOP turnout suggests some union members may have crossed the aisle to cast votes. Rauner beat Dillard 40 percent to 37.

Rauner’s aggressive talk about the state’s “corrupt union bosses” occurs against the backdrop of Republican reforms that have rocked its neighboring states.

In Wisconsin, governor Scott Walker fought and won a major battle to curb the collective-bargaining rights of the state’s public-sector unions; in Michigan, governor Rick Snyder led the fight to pass a right-to-work law that protected workers from paying compulsory union dues; and in Ohio, governor John Kasich passed a broad law limiting collective-bargaining rights that was overturned in a referendum a year later.