Sssshhhhhhhhhhhhhhhh.... they haven't thought of that one yet.
Actually, my error it is 3/5ths count, not 2/3rds count in the original Article I, section 2, clause 3. And as all good FReepers know, it was to prevent Southern Slaveholders from getting greater representation in the US House by counting their non-voting, non-citizen slave populations as equal to the populace of the non-slave states.