Political emails are spam. No matter from which direction they come from. So tagging them as spam seems just the right thing to do.

Political emails often are spam but not all of them. I subscribed to few newsletters from various political parties and I don't want google to block them from me.

It's only spam, if you don't want it.

If you explicitly solicit those emails, eg by signing up to a newsletter, it's not spam.

Some of the conservative emails I did not opt in, so could be considered spam. Others I did opt in and it still gets sent to spam.

On the other hand I get unsolicited email from some Democrat groups, and I never see such emails in spam.

I'm liberal, and lots of the unsolicited Democrat emails go to my spam folder.

I've heard people in the political world talk about buying and selling email lists, which I thought was illegal, but seems to be common practice.

In the early 90's I gave something like $20 to the Sierra Club or a similar group. After a deluge in physical mail asking for donations from around the political spectrum, I never did it again. I left no forwarding address after moving either. Pretty dumb on their part, they traded all their goodwill for a short-term dollar.