"You'll never be one of them."
--Captain George von Trapp (The Sound of Music)
Many people mock the inability of Republicans to stand together on a variety of issues. Look at the Democrats, they say. Dems have the ability to die to one's self, to take one for the team, to stand in solidarity.
Why is such unity deemed valuable? Because in a democratic political system numbers matter. If you can somehow get enough otherwise diverse factions to band together with you then you can gain control of the strong arm of government.
This is why liberty and democracy are fundamentally at odds. Those willing to compromise in order to join a majority faction are prone to give their freedom away.
This is also why collectivists are attracted to democracy. By definition, collectivists emphasize group over individual interests. They are more prone to compromise for the sake of the collective.
Preference for collectivism can be seen as distributed across a spectrum:
Highly collectivist preference <------------------>Low collectivist preference.------------------>
Preference for collectivism should be inversely related to preference for liberty.
It is safe to say that people with more collectivistic tendencies will be attracted toward the Democratic Party while people with less collectivistic tendencies will be drawn toward the Republican Party.
Because they are less collectivistic by nature, Republicans are more prone to break ranks and disagree on issues. This naturally puts them at a disadvantage in political systems grounded in first-past-the-post political processes.