Michelle Rhee, the former chancellor of DC public schools, has an op-ed in Washington Post today weighing in on the fallout of the recent Chicago teachers strike.

She argues that Mayor Rahm Emanuel’s stance – pushing for the teacher evaluations that unions opposed – shows that even progressive Democrats are coming to view teacher unions as an obstacle, not a partner, to education reform.

Rhee claims that by opposing these evaluations even when liberals propose them, teachers unions are gradually losing the broader debate on education reform:

Going forward, I suspect more Democrats will say, as Emanuel and President Obama have, that it makes sense to look at how much children are learning when assessing a teacher’s work and to empower parents to help turn around schools that are failing their kids, and that it is right to pay teachers more but to also hold them accountable for results.

I know that opposing unions on some of these policies isn’t easy. But the more that unions continue to attack fellow Democrats, casting everyone who challenges their policies as “anti-teacher” or “anti-union,” the more they isolate themselves from the broader Democratic Party.