You might think that most people hold that view and I would guess that a lot of the people I socialize with would agree but the majority of Americans don't. That's why people like Jon Huntsman didn't win the Republican primary in 2012, Chris Dodd got almost no votes in 2008, and plenty of other candidates have fallen into the same trap (Chris Kelly, for instance, lost badly in the 2010 California Democratic Primary for Attorney General). If Americans really didn't agree with either party, you'd see them winning but the only real insurgent challenge is coming from the Tea Party on the far right.