Here Romney boasts about the positive nature of his weak anti-Huckabee attack ad.  I’m sorry, but when you’re running against someone who has stratospheric favourability ratings you really have to do more than draw “contrasts” in a good-natured way while emphasising just how wonderful your opponent is on other issues.  Immigration activists seem to be gravitating towards Huckabee despite his record, which some of them must know about already, and they are doing so in surprisingly large numbers.  When your opponent is receiving the endorsement of the Minutemen, you cannot effectively get to his right on immigration.  You have already lost that battle.  Fiscal conservatism and tax policy are Romney’s strengths with Iowa voters, but these are not the kinds of issues that drive large numbers of caucus-goers.