The straw poll is nonsense, but he would be foolish to skip the caucus primary. If he does, that would give a better opening for Kasich if he runs to make some headway. Katich more than Walker is the guy he really has to worry about. Rubio too, but I have this feeling that Rubio is going to flame out. His base is not very deep, although wide. He's really an establishment candidate. We shall see.
McCain skipped the caucus. Romney gave it mild attention until the very end.
But Bush vs. Walker or Rubio is starting to remind me of Clinton vs. Obama 2008 so I assume Bush wants to avoid another candidate getting such a large bounce from an Iowa win that his NH support collapses.
