In Iowa, it's all about the ground game. They don't have a primary election, so you can't just mail in a ballot. You have to actually show up at your local caucus, and then you have to stay there until they are done. Trump went to a few big events where a lot of supporters showed up. But were they from all over the state? It does you no good to win a few caucuses with most of your supporters. You need a majority of supporters to show up at a majority of caucuses, and stay there until they finish.
Each caucus takes a preliminary vote, and anybody with too low a percentage is out. That solves the problem of too many candidates. Their supporters go find another group to join. If Trump's support is fixed at a maximum of 49%, he can still lose a caucus! The caucus will eliminate the minor candidates, so Trump's supporters may face just one other candidate.
I wonder if he can break that 50% support line? Are his supporters the old-style politically-active people who actually get the turn-out to caucuses, or are they a very enthusiastic 35% who have never been to a caucus and won't know what to do? You just go there yourself, and your vote gets cancelled out by the woman who drives a van full of people there. Or the church that drives up in a bus to vote for Cruz!
