Bush 26%
Trump 23%
Rubio 7%
Cruz 5%
This part is quite telling. It's just very unlikely that Trump will win Iowa - especially now that he's almost lost his lead there - and highly likely that either Cruz or Rubio will win it in the end (if not Carson reemerges there, which he very well could once the media attacks are dimming down on thim). I'd say that it's an 85-90% chance at this point that either Cruz, Rubio or Carson will win the Iowa caucuses. Since caucuses are so diametrically different from primaries, in the way that a candidate ultimately has to garner support even from voters who don't have him or her as their first choice, it just makes the chance of Trump actually winning Iowa infinitely much smaller. Near all of the Bush, Kasich, Christie, Paul, Huckabee, Santorum, Fiorina supporters will rather support Cruz/Rubio/Carson than Trump. Almost every poll ever released show this to be a very clear fact. Together, Cruz/Rubio/Carson have almost twice the support as Trump already, and that will only increase as voters get more serious and stop paying attention to Trump's endless drama and childish attention seeking.