I happen to believe that all prominent politicians lie, and that the ones who aspire to presidential level lie most egregiously. Some do it with enough charm, bravado and support from their supporters to (usually) get away with it. But they lie, and the followers who think that "their guy" is different are lying to themselves.
Here we find the Washington Monthly setting up something they call "The Mendacity Index" which lists and rates falsehoods from Reagan, Clinton and a pair of Bushes. It's a gimmick and one could certainly argue that the examples chosen could be more exhaustive. Still, it makes a good point.