Assuming you're in the US, it's my understanding that political affiliation is generally not a protected category. So if it's at-will employment at a private employer, it's probably legal to fire you for your political beliefs / actions (or "no reason" when it's really about political affiliation). If someone is engaging in behavior that bothers you, tell them to stop. If they don't, report them to HR. Make sure everything is in writing. But, be aware that HR might not be on your side; but at that point you really need to reconsider whether you want to work at a place where you are harassed and not supported by the company for not discussing politics.
Some high level laws by state: https://www.legalmatch.com/law-library/article/political-aff...
The City of Seattle "assure[s] equal opportunity to all persons, free from restrictions because of race, color, sex, marital status, sexual orientation, gender identity, genetic information, political ideology, age, creed, religion, ancestry, national origin, honorably discharged veteran or military status or the presence of any sensory, mental or physical disability."
https://library.municode.com/wa/seattle/codes/municipal_code...