Part of McCain’s surge is his dawning awareness that he must take Rudy out early if he’s to have any chance at all for the nomination. The truth may be that if both he and Rudy poll fairly well in New Hampshire the real winner will be Romney.
So: Maybe the main threat to Rudy hanging on until Febrary 5 against the early Romney victories is a resurgent McCain. A "secret weapon" Rudy may have against being blown out early by Romney is Huck doing well in or winning Iowa. Both Huck and Obama threaten Rudy’s Iowa’s momentum. An Obama victory there would take most of the attention away from the Republican result. But an Obama Iowa victory would also make the Democratic contest in New Hampshire irresistable for independents--most of whom would otherwise vote for Giuliani and McCain. So, on balance, an Obama victory in Iowa might well be fatal for both Rudy and John.
Maybe the worst thing that could happen for "national security" voters is the persistence of the McCain surge; its effect would mainly be to undermine Giuliani. The worse thing that could happen for "social conservatives" is the persistence of the Huckabee surge; its effect would mainly be to undermine Romney. This analysis, of coruse, makes no sense to anyone who really believes that John and/or Huck have decent chances of actually being nominated. But it’s still hard to deny at this point that Rudy and Mitt are better bets.