The whole public school culture is toxic to conservative values. There are dissenters. In fact, there are many of them, but when they express that dissent, they are crushed and shamed by the rest. It's not just, "we disagree with you." It's, "you're a bad and selfish person who doesn't care about anyone but yourself." Nobody wants to be the one person in the room getting yelled at and judged by 40 people, so they keep quiet.
It's anecdotal, but as you would guess, we know a lot of public school teachers and librarians. The liberal ones have Facebook pages full of political crap and routinely talk politics - both online and at school. They are proud leftists and have no filter at all. The conservative ones don't post conservative stuff. They just don't post anything political and never talk politics at school.
I think it varies by location. I promise you the teachers where I live are nothing like that....which is why I chose this place to live the last 25 years.