@Catija I wonder what options people have when they believe they have specific reasons for someone not to be a moderator, apart from commenting on their nomination, or mentioning it in the chatroom? Once the election starts, those who didn't happen to see those comments, will probably not get the message. My understanding is that writing Meta posts directed specifically at negative aspects of a certain user, are strongly discouraged.
I know there is a "contact us" button, to contact CMs, but I think this mechanism would only be effective in extreme circumstances. If there is no reason to remove a nominee from the candidate pool, but the community still has concerns about that user that they want more people to be aware of before they vote, it doesn't seem there's any way for them to get the word out.