As far as where the opposition to his ideas are coming from, even within GOP ranks, it is my belief that he is simply labeling that opposition as “neo-conservative” because of the pejorative value he believes it has. However, I don't believe that opposition - conservative, moderate or liberal - is derived from or a result of anyone, specifically, arguing from a “neo-conservative” position.
"Neo-con" is just an empty pejorative. It has no meaning beyond the intention of conveying a meaningless, non-specific negative impression.