Is it a conflict of interest to recruit union membership and fight state wide charter schools?

I am a teacher/ administrator in a state wide cyber charter school in Pennsylvania. My concern is that we are a school of choice. For whatever reason we have attracted a majority of politically conservative parents and students. I am concerned that they will become alienated from the teachers when they find out how much of the money goes to liberal causes.

I am also concerned that our state teachers union, the PSEA, has gone on record as being against state wide charter schools.  http://www.psea.org/uploadedFiles/LegislationAndPolitics/Legislative_Updates/PSEAPosition-AmendmentsToSB560.pdf

Isn't it a conflict of interest for them to proselytize union membership and be on record as being against our school;s existence at the same time?