Only he didn't compare Obama to Hitler.
He was merely making a hamfisted analogy: A is to B as C is to D.
He could just as easily have said expecting Obama and Boehner to come together is like expecting Netanyahu and Hitler to come together.
Besides Obama is much worse than Hitler. Obama is a liberal progressive socialistic communistic fascistic totalitarian gun-grabbing drug-taking pro-abortion homosexual islamic antisemitic pedophile.
Hitler was just a liberal progressive socialistic fascistic totalitarian gun-grabbing drug-taking pro-abortion homosexual islamic antisemitic pedophile.
/sarc
As an aside, the Obama/Hitler analogy is ridiculous, except that both are objects of intense hatred. I compare Obama more to Putin or Chavez than to any one else.