How does this happen

Today I was watching a piece on PBS about all the film people who fled the Nazis and how their contributions really changed Hollywood.  A thought came to me, what would the world be like today, if instead of Hitler coming to power in Germany, if his character came to power in America?  I wonder if that alternate reality has ever been explored in a novel.

The world would certainly be a different place… but would it be worse than the Bush administration?