The voters. If the voters elect crooks, they deserve to be robbed. If they elect killers, they'll get what they deserve there, as well. And if they don't like who the other guy elects, they can always move.
And if voters elect a moral conservative for president who believes it’s the federal government’s job to protect human life, anyone who doesn’t like that can move to Europe where the state murder of crippled “useless eaters” is a tradition.