My suggestion is that political posts not be voted up or down. The downvote, though this is not done according to the rules, is generally used to disagree. In political posts it often is used to silence a poster or to attempt to shut down a discussion. The best way and best reason to shut down a discussion is when it gets too unwieldy and the moderators did shut down a political discussion recently

Another option might be to allow downvotes only, not upvotes, and require the voter explain why the post does not add content value to the circle or doesn’t belong in it