(understand not Kerry)
In a nutshell: McCain is too old, Clinton is Bill's wife, Romney if from MA, Guliani is also from the NE, Obama is too inexperienced, ...
http://www.msnbc.msn.com/id/16564949/
....
As for Edwards, the heel he'll have to overcome is the one of authenticity. Edwards, both in '04 and now, says things that a lot of voters want to hear. But how will voters know this is the "real" Edwards and not the one that was trained as a trial lawyer and therefore comfortable making any argument well? Edwards has gone through a subtle political transformation, one that is actually understandable and believable. But his authenticity will be questioned (why did he support the war in the first place, why did he support such-and-such agreement when he was in the Senate... etc.). There's no silver bullet to "prove" to voters that one is "authentic;" they just have to be won over with time.
It seems that early on, Edwards realizes this may be an issue. It may explain everything from his unorthodox pick of David Bonior -- never one for showing off strategic skills, who seems much more of a "message" pick than a "strategy" pick (and I mean that as a compliment) -- to the Web-based reality series on Edwards' campaign. This could help, but he's got a long way to go.
I do not agree with everything in this article, but the media framing has already started very hard.