When Chicago public school teachers started the fall semester by turning down a $400 million contract offer that would have boosted pay by 16 percent over four years, "my first concern wasn’t for the children," writes Tim Cavanaugh. "It was for the Democrats."

Sure, the walkout by Chicago Teachers Union members caused havoc for kids. "But I’ve been to public school," Cavanaugh continues, "and I can tell you they didn’t miss much."

The strike’s lasting damage was to the party that since at least the early 20th century has been labor’s best friend.