I always seem to end up in the US at election time. Mind you, as the whole thing takes over TV for a year & I spend up to a few months a year there, it's hard to avoid that. Each time, the whole thing becomes more inane.
Anyway - here in the UK - you can vote for whoever you want. It won't make any difference to the cultural changes that are occuring. Judges, Police & civil servants are not elected officials & yet, the amount of decisions these people can make regarding to your culture is frightening.
Just last week a white English family was refused permission to hold a funeral on a Saturday whereas this same local council permit muslims to have funerals on Saturdays. How many English people agreed to, voted for or were told about this policy ? People are making up these rules outside the political arena.
If you are worried about your culture I don't think you should spend too much time worrying about who the PM/President is. It's much better to spend your time worrying about the people that are actually making decisions both above & below the PM/Presidents payscale.
I'm not sure if the US is much different in that regard. I will say though that the UK are being particularly nonchalant about the cultural changes occuring right now.