They can't help it. Anyone who exhibits one or more of the "dark triad" can only pretend to feel anything. The only thing that "gets them off" is bossing others around (by force, coercion, deception, politics, etc.). And studies have shown that the recognize each other at very early ages. Look up Political Ponerology.
Forget party. These people have a "dark triad" of brain problems, Call it "essential psychopathy", Satanism, "psychic vampires", witches, whatever. They are not like us, they comprise approximately 5-10% of the population, and they are drawn to positions of power like moths to a flame. They aggregate (political parties, gangs, agencies, police forces, etc.) where they can wield and abuse power. They recognize each other by what they lack, but they can "pretend" (in a limited fashion) to be "normal". Search out "Mask of Sanity" by Hervey M. Cleckley. You'll find it free on-line. We are witnessing the first time in history where anonymous autists (us here) are defeating psychopathic narcissists, and they will fight until the end.