If the Democrats and the Republicans ran a drunken hog and a poisonous swamp viper for President, the same people would still go out and vote for them, because there would effectively BE no one else to vote for!

And that, basically, is how it's done. One party, falsely posing as two parties, puts forth 2 phony lines of rhetoric, trots out 2 controlled creatures it pretends are real "candidates", the public votes one of them in, and the farce goes on for another four years. Almost no one in the world is fooled, except a sizeable chunk of the American public...enough to keep the farce going.