What’s behind the recent spate of teacher strikes from Los Angeles to Denver, West Virginia, and Oakland? Local issues like across-the-board raises and increased educational spending are certainly a big part of teachers’ demands, but they could have been fought without a strike. The larger issue at play, and the real reason for these strikes, is a shift in the landscape of the party the teachers’ unions have always called home.

The Democratic Party continues to drift away from centrist ideas and toward a more “progressive” approach to labor and education, and teachers’ unions are prepared to exploit this shift. In a very real way, the teacher strikes across the country serve as a signal to the progressive left within the Democratic Party that union support is contingent on falling in step with their demands. Gone are the days of Obama-era bipartisan support for charter schools, teacher accountability, and merit pay. In addition to increased school spending, that means ending the use of merit-based pay and hindering the growth of non-union charter schools, and the progressive left, for better or for worse, is prepared to acquiesce.