I would take offense to anyone telling, or suggesting, to me how to vote. "Implied intimidation" is as bad, if not worse, then "direct intimidation".
What if a Koch employee was fired for not voting for a "suggested" politician?
I would take offense at it as well. But is the offense of my delicate nature worth quitting over? It's a toss up given the issue. But I don't think them sending me literature is illegal.
Fired for not voting? How would they know? I ain't gonna tell 'em if I need the job.
In the same way that I don't advertise my horrible drinking problem and propensity to stay out late to my employer, I don't think I need to talk politics with 'em. Smile and say "yes sir" unless something they need me to do in the course of my job presents a serious ethical delimna.
Campaign literature is just one of those dumb ass things like, say "admininstrative professionals week", that I just kind of ignore. I don't wanna go to your fuckin ice cream social and I ain't votin' for no tea party savage. Same thing.