http://www.gop.com/images/legal/2008_RULES_Adopted.pdf It's on page 44 of the document, Rule 40(b). These were the rules that were adopted at the 2008 convention. It says later on that these rules are temporary for the 2012 convention, which would mean a new set of permanent rules would have to be adopted by the floor and passed. The media misleads us when they talk about Jeb Bush or Chris Christie "jumping in" if it goes to a 2nd ballot. As of right now, that's against the rules. The question is, what rules will the delegates adopt and pass when they convene? Who knows.