The Chicago Teachers Union, or CTU, showed a keen sense of timing by going on strike yesterday. All the stars were in alignment for the union: a strike in Obama’s adopted hometown, against his former top aide, in September of his re-election year. The teachers thus gain maximum leverage against the White House and have an excellent chance of forcing a resolution in their favor. Their small war against Mayor and former White House Chief of Staff Rahm Emanuel disrupts Democratic unity at a critical time and marginally disrupts union-led efforts on Obama’s behalf in nearby states like Wisconsin and Iowa.

But if the strike is good for the teachers, it’s also good for Republicans: It brings back to the forefront the same political issues that Wisconsinites have been dealing with over the last two years. And it highlights, once again, the dangers of exempting large groups of government employees from the legislative process through monopoly collective bargaining agreements.