Usually, in any dictatorship or totalitarian government there is no "choice." The leaders of a particular party or faction of the previous government overthrows, assassinates,
… exiles, or otherwise eliminates any other possible leaders. Or a party is chosen through an election (some are staged) and then the elected party chooses the head of state, who then declares themselves the dictator, supreme ruler, emperor, or what ever else they deem appropriate. And they usually disassemble any parliamentary or representative bodies of government or some like to pack them full of allies and imprison, execute, or banish any political, academic, or ideological opponents. (MORE) 
