In a comment to this question Kortuk says
I cannot cast a single close vote, ever. This has been requested but it has been decided that moderators only cast complete votes.
Was it discussed here on meta? If so, I can't find it, but I would like to know the reasons. I think a mod should have the right to a personal opinion too, and say: "Look, personally I would think this should be closed, but I want to see what others think", instead of: "Look, I would think this should be closed, so it will be closed." Big difference, if you ask me.
OTOH, the mod would still be able to cast a vote by creating a second non-mod account, but I think this won't work at all.