I'm a stickler for people following their own rules, which is why I don't read a lot of fantasy novels - most fantasy authors keep making up rules and exceptions to them as they go, and that's cheating. I like sci-fi because once the nature of the broken rule is established (warp drive, time machine, silicon life forms, etc.) the author stays within that framework.
The rules for Obama were simple:
1. There's an election by the delegates at the convention. No matter what the pundits and second-guessers say the vote total will be, it's not over till the delegates vote.
2. You don't get to choose a running mate until you are the official candidate.
It's called democracy. Obama apparently prefers the Chicago-style version.