I'm fine drawing a line for an officer carrying out election duties that goes further than for other people.
They just shouldn't wear anything that puts the election workers in a position where they have to evaluate the political message. I guess that can be tricky if a uniform somehow became partisan though.
There likely is a moderately sized group of people who are opposed to having police, but the real partisan divide is over what sort of policing is acceptable, not over policing itself.
And even that is not really a sufficient explanation of the differences in opinion, it's too simplistic. People disagree about whether police are biased and things like that.
They just shouldn't wear anything that puts the election workers in a position where they have to evaluate the political message. I guess that can be tricky if a uniform somehow became partisan though.