In my opinion a Christian should not promote sin. so as long as the politics are not encouraging or legalizing sin Then there is no need to mix.
Supposing however that someone without a religious preference were to vote, we wouldn't think twice about them voting for what seems the more moral of the options to vote for. And in these Cases most Christians already know their moral guideline in the Bible. and for many there is only one way to live (even if they arent' living it themselves) so if you have a moral code or rules that you live by of course your own political preferences are going to follow that.
Therefore if your preferences are based on religion there should not be any problem to base your political beliefs on what the Bible (or your religious doctrine) teaches