Put aside for a moment the particulars of the Chicago teachers’ strike and look at the broader picture. Rahm Emanuel is only one of a number of Democratic mayors and governors who are going after public-employee unions. In Los Angeles, Mayor Antonio Villaraigosa is also at loggerheads with the city’s teacher union. In San Jose, a Democratic mayor and city council scaled back the city employees’ pensions (and so did city voters when they were asked to ratify that decision). In New York, Governor Andrew Cuomo has tangled with a number of public-sector unions. The battle between management and labor seems to have spread to the very center of the Democratic Party.