Noah Millman thinks that Huckabee is the obvious veep pick for McCain, but not for other candidates. I’m not sure why. Giuliani might need Huckabee as a social conservative, and Romney might need him as an evangelical. I think McCain would be fine with both groups. Huckabee’s odd move yesterday–unveiling a negative ad against Romney and then declaring his unwillingness to run it–will make all of these guys more wary of him, whatever impact it has in Iowa.