One other thing to watch will be the weather. Right now, there looks to be some snow moving in around caucus time on Monday night. Here is the current NOAA forecast in Des Moines:
Finally, we have the viability threshold. At a Democratic caucus in Iowa, votes align themselves into groups under a candidate. With a 3 person race, 15% is viability at the precinct level. If, at that particular precinct, O'Malley can't get 15%, his supporters either move to undecided to be swayed into a camp, move into another camp or just go home. How infrequent he hits viability and where his supports land will also tilt the scales.
-As I was writing this the Clinton camp got new news: More emails now that were not classified at the time according to the state department's spokesperson John Kirby. This continues to confirm that the former Secretary has been saying for the length of her campaign. Whether the American people will be able to comprehend the difference between then and now is another story that could continue to prove difficult for the Clinton camp. Though, this likely would be more of problem in a general electorate than in an Iowa caucus where the only people to show up are the most engaged voters that have been following the story from day 1 and have head all sides of this ad nauseum.