>>It's something that the Kerry campaign will be forced to address regarding a previous criticism of Bush's foreign policy<<
That won't be good enough for the "undecided." The "undecided" are not undecided about world events and anyone who thinks that's their problem is in for a rude awakening.
So the scandal has to be something more simple than the War...something more personal and dirtier like: Kerry is a Closet Lesbian.
Anything that requires people (especially the undecided) to think, will not work.