Why?: Because both are libertarians, and perhaps even conspiracy theorists who don't trust the government at all or any figure more powerful than they are even they themselves are much more powerful than the common person.
Now to point out the obvious
top: Al Gore bottom: Captain Planet
Why?: Is this joke not obvious?
top:Hillary Clinton bottom: Mystique(I know the face is kind of funny in this pic no clue why)
why?: They changed based on how it benefits them.
top: John Mccain bottom: The Incredible Hulk
why?: You wouldn't like him when he's angry
top: Mike Huckabee bottom: Spiderman
why?: They both actually have a sense of humor
top:Barack Obama bottom:Green Lantern
why:? A. they both talk the same B. They're the only black people on their team