It depends.
If Kerry, and the rest of the Congress and Senate, knew everything the President knew, including what he thought he knew, and what he says he thought he knew, but didn't know after all, then yes.
If not, then there is some responsibility remaining for the vote, but if they acted on spin, they are more guilty of credulousness. It's a sad thing, if trusting the Executive branch on matters of highest security and life and death turns out to be an exercise in credulousness, but live and learn. If they believe him again without a higher standard of evidence, then shame on them.
Regards--
Mary Anne