I know in CA it is a violation of election law for an armed law enforcement officer to enter a vote center unless they are responding to an incident or there to vote.
That, in my opinion, is the question of the era for the USA. We were taught that the rule of law prevailed and there are "checks and balances" but it seems like there is no prescibed way to enforce the rules inside the system.
Different cops. We had sheriff’s deputies out for some other issue, my impression was they took the law pretty seriously. They may not arrest them on the spot, but I think they would get ID and tell them to leave, and later file a report.