I think the explanation is a combination of candidate weakness and a steep learning curve that often characterizes the early caucus and primaries. Although the evangelicals (who seem to make up about 45% of likely caucus supporters) know what they like, they didn’t know that much about these candidates. So what we’ve seen is a learning process in which each potential non-Mitt candidate (they already know they don’t like Mitt from 2008) was examined and each was found to have flaws. Bachmann too “flaky”, Perry a bit unsteady in debates, Gingrich got pummeled with unprecedented negative advertising highlighting the non-conservative aspects of his record, Paul is more libertarian than conservative and that leaves Santorum as the last conservative standing – for now! He’s out to prove the old biblical adage – “the last will be first”.