". It is widely believed that incumbents cannot win if under 50% in approval because undecideds will largely decide against them. "
I know this is a wide belief. It is a mistaken one, however. There is no evidence to support the belief that undecideds break to the challenger in Presidential elections, and a good amount of evidence that the opposite is true (see both this article and the one on my site called "Breaking Conventional Wisdom".
Well, I am glad to be wrong about this. It also leaves me free to part company from Dick Morris - a twofer.