At the beginning of January, Iowa looked as though it was Ted Cruz's to lose. According to the Real Clear Politics average of recent polls in the state, the Republican presidential candidate's lead slipped and then Donald Trump surged ahead. In the last five polls RCP uses in its count, Trump has led by five, 11, seven, two and seven points respectively.

That most recent seven-point lead comes from Monmouth University, which saw Trump regain the lead from Cruz since the last time it polled, in December. It's the second time that Trump has fended off a usurper in the state. The first time, the threat came from Ben Carson, who has now all but vanished.

Maybe Trump will hold that lead over the next few days, who knows? As a perpetual reminder, Rick Santorum trailed in Iowa by 15 points a week before he won the caucuses in 2012, so it's very smart to assume that things could change dramatically.

But polling often does a poor job of predicting one of the most important aspects of what will happen on the night of the caucuses: Who will turn out and for whom. I've been on a bit of a kick to this effect for a few days now, but I can't reinforce it enough. If Trump or Cruz can't get their people to the polls, an easy race can become a close race and a close race can become a disaster.

We noted on Tuesday that Trump's base in Iowa is less likely to turn out, which is a problem for him. There have been conflicting reports about Trump's ability to get those people to the polls. CBS raves about his campaign's use of an online tool to organize. The Times is skeptical.

To turn out supporters, Cruz's and Trump's teams need to know whom to turn out. They need to have built up lists of people to call on Monday, encouraging them and reminding them and cajoling them to participate.

And buried a bit in that new Monmouth poll is a question that can help us assess how the campaigns are doing in that regard.

Have you personally been contacted by a campaign?, Monmouth asked. Nearly half of poll respondents said they had.

And who had contacted them? (Monmouth allowed multiple answers here.)

A quarter had been contacted by Cruz. Seventeen percent had been contacted by Marco Rubio. And 13 percent — about half the level contacted by Cruz's campaign — had been contacted by Trump. It's about the same as the number who reported being contacted by Carson's team.

It may not matter. Trump may be up enough that if his turnout game isn't strong he'll still walk to victory. The weather forecasts, which predicted cold and snow on Tuesday, have shifted slightly in the eastern part of the state, probably meaning that turnout will be higher. There are a lot of ways in which this figure isn't destiny.

But it's not what I'd want to see as a campaign manager. A campaign that has just surged into first would be well-served by also being in first in the outreach game. If Cruz eats into Trump's lead over the next five days, Santorum-style, that field effort could make a big difference.