The answer: One Republican and One Democrat/Independent.
The Iowa Caucus is pretty much up for grabs in both parties. Over recent days, a clear Trump lead has been erased, and Cruz is now ahead in recent polls. Over roughly the same period, a clear Clinton lead has been erased, and Sanders is now ahead in recent polls.
FiveThirtyEight (Nate Silver) is still predicting a Clinton victory for the Dems, but a Cruz victory for the GOPs. The Clinton victory prediction is of high confidence, while the Cruz prediction is not, and Trump is close behind.
One way to look at the polls is to track changes and put a lot of faith in the most recent information. Another way is to use as much data as seems relevant (even looking outside polls) and assume that this gives a better prediction, and go with that. The latter is the method used by FiveThirtyEight. So, Nate Silver’s method will be a big winner if Clinton and Cruze cinch the Caucus, but not so much if Sanders sandbags Hillary and Trump trumps Cruz.
People put a lot of significance on the Iowa Caucus because it is the first real contest among candidates. But then, after the caucus has become history, they are less likely to care too much about it. How important is it as a predictor of the outcome of the entire primary season?
That depends on the party.
Barack Obama, John Kerry, Al Gore, Bill Clinton, Walter Mondale, Jimmy Carter and George McGovern all won the Iowa caucus (or came in above the other candidates) and went on to be the Democratic Party nominee. Dick Gephardt and Tom Harkin also won the caucus, but did not become the nominee. One might say that the Iowa Caucus predicts the nominee pretty well for Democrats.
Gerald Ford, Bob Dole, and George W. Bush all beat the other contenders and went on to get the nomination. But most of the time, the Iowa Caucus was either won by an unopposed Republican (so we can’t count those years in assessing its significance) or was won by a candidate other than the eventual nominee (such as Rick Santorum in 2012, Mike Huckabee in 2008, and Bob Dole in 1988). Overall, the Iowa Caucus means little in the Republican Party, if we go on history, especially in recent years.
Despite FiveThirtyEight’s claims, based on a good analysis of hefty data, I’m going to say that there has been too much flux in the polling numbers to call the caucus at this stage, just over a week prior.