Make sure you write down everything he says or everything that happens around you. Note it and show it to someone at the time who wont out you, maybe someone at home.

Have a trail of paperwork and corroboration that what happened, happened.

If your work email is not secure, use a personal email account set up for this purpose only.

And tell that person the story so it isnt just something made up, which it isnt of course.

If they bring up anything political you could just smile and say, "I really prefer not to discuss politics or religion at work" and change the subject to something work-related or neutral.

that shit about Hillary, they will often harp on it over and over and over. Making life impossible.

for information, General Wesley Clark has been a good friend of both HRC and Bill (tho I've complained she never did anything FOR Wes, but that's just me.)

I'm on a crew of eight. Six are ex-military. They think they have to be conservatives.
We generally work in pairs repairing or rebuilding machines. Two guys in particular have
relatively open minds if you supply them with a few facts.
Example: One guy said something to the effect that when Obama cut the military budget....
I explained that all spending bills start in the House of Reps. The President doesn't write the bill.
He can either pass it or veto it.
They have both told me they enjoy talking with me and they learn something every time we talk.
Turned them on the Vote Vets. Now they have less need to tow the conservative line.
We're making progress. They actually come to me with questions about Government.
Minds can be changed with facts.

1. They will not accept responsibility for any errors.
2. They will attempt to take credit for any successes.

We caught a RWer stealing. He denied it even as we showed him the video. Management showed him the door. He still denies it to this day.

They are very cultish. You haven't barked at any dog whistles yet so they know that you are not one of them. They have been conditioned and trained to believe that they are always correct and you are always wrong.

Watch your back.

are a Liberal/Democrat, they likely have the right to do that. Pretty sleazy, but such is life nowadays. They might never say that's why you were dismissed; but even if they did, not likely much you can do about it in the scenario the OP presents. There are a few states with laws that prohibit certain types of political coercion, but it doesn't sound like that is the case here. You should check with an attorney in your state.

I'd just avoid the issue with the trainee.