Teachers' Unions find an issue that can appeal to those who are not big fans of public employee unions.

"Scott Walker, the Wisconsin governor and possible presidential candidate, stoked national attention when he stripped collective-bargaining rights from most public-sector unions, including teachers. But testing, [said Nelson Lichtenstein, a labor historian at the University of California, Santa Barbara], offers unions a way to join forces both with parents who object to testing and with Republicans who oppose the Common Core standards as a federalization of education. 'It is a powerful issue, by virtue of the fact that the right is also against it,' he said."

From a NYT article titled "Teachers� Unions Fight Standardized Testing, and Find Diverse Allies."

The teachers� push on testing comes as Congress is debating how to revise the 2001 No Child Left Behind law...

Critics of the campaigns against testing, including many state and local education officials, say the unions are not acting out of concern for children but are trying to undercut efforts to institute tougher evaluations. They argue that annual testing is critical for tracking how effectively schools are educating poor and minority students and that evaluations based only on subjective criteria like observations typically fail to identify weak teachers....

Secky Fascione, director of organizing for the National Education Association, the largest nationwide teachers� union, said reining in testing was the union�s top organizing priority. In the past month, Ms. Fascione said, chapters in 27 states have organized against testing, including holding rallies; petition drives; showings of �Standardized,� a documentary critical of testing; and sessions telling parents they have a right to keep their children from taking tests, as tens of thousands of parents around the country have done.

�Does it give us a platform?� said Karen E. Magee, the president of New York State United Teachers. �Absolutely.� 

The union of left- and right-wing ideology. Who's leveraging whom? Or is this the serendipitous coalescing of natural interests?