Kerry says one thing one minute, and then the exact opposite 10 minutes later. His voting record looks similar to a pub dartboard after a blind man steps up to play. You can only blow in the wind for so long.
The Iraq war "excuse" is like a colossal version of Clinton's famous "I smoked a joint but I did'nt inhale". The media and the Republican party will burn Kerry to the ground over this and other credibility gaps. He'll spend his debate time trying to spin his record every which way he can. Of all our candidates, he is the one with a level of credibility most closely approaching the Bush Event Horizon, beyond which no truth can emerge.
Are you all really, really sure that you want to nominate this character? The "electability" meme being associated with him is just PR, nothing more. He is not honest, candid, or energized. He has no vision or ideology or principle that he represents. He has no plan for the future that does not seem like a momentary contrivance designed to pander to whichever voter group he is speaking in front of at whichever moment. His voting and public statement record turns attacking his credibility into shooting fish in a barrel.
Remember "Will the real George Bush please step forward"? Remember how effective that was? Do you want the 2004 election campaign, with all the hostile media a Democratic candidate is already expected to receive, turning into "Will the real John Kerry please step forward"?
It'll happen, if you nominate him.