The election system is bugged, it doesn't allow the republicans to campaign in some of the states, resulting in the opposition party to endlessly build up support that you can never overcome.

Or is it by design that the democrats are defaulted to win? I have seen that before in a few mods.

Edit: I am guessing its by design the democrats win, because I noticed outlawing the KKK focus increases support for the democrat party, which makes no historical sense at all.