Placard politics: Perhaps the simplest and most convincing counter to any "Bush Lied" rhetoric is that there is no chance that, knowing we'd find no WMD, Bush would have allowed the case to be made so strongly that we would. It's political suicide, and he certainly couldn't have gotten Colin Powell aboard, which was a necessary part of the pitch.

Unfortunately,

Bush unknowingly placed too much credence in intelligence estimates from multiple parties because they supported his pre-exisitng expectations, largely influenced by advisors still stinging from their decision not to pursue the Iraqi army into Baghdad in 1991

is real hard to fit on a sign that you can carry into the convention. John Kerry can't make that case seriously, and that's why he'll lose in November.