So far, the higher the turnout, the better Donald Trump has done:

In Iowa, about 8 percent of the voting-eligible population participated in the Republican caucuses, according to a calculation by Dr. Michael McDonald. Trump won 24 percent of the vote.

In South Carolina, 20 percent of the voting-eligible population voted in the Republican primary on Saturday. Trump won 33 percent of the vote.

In New Hampshire, 27 percent of the voting-eligible population participated in the GOP primary. Trump won 35 percent.

Is this a coincidence? Probably, at least in part; it’s hard to make very much out of three data points, and there are several conflating variables. For instance, there’s been evidence for a long time that Trump is more popular in both the Northeast and the South than in the Midwest. Also, several candidates dropped out after Iowa and several more still after New Hampshire; even if Trump is picking up less of that support than other candidates, that still helps him some.

Nonetheless, if you’re Ted Cruz, this might give you some explanation for why you beat Trump by 3 percentage points in Iowa but lost to him by 10 points in South Carolina. Even though Republican turnout hit a record high in Iowa, it was still much lower than it would be in a typical primary, since caucuses discourage participation and disenfranchise voters. Cruz’s ground game had more opportunity to make a difference in Iowa, and Trump had less of an opportunity to benefit from irregular voters who might show up for Trump but wouldn’t typically participate in a GOP nomination contest.

We’ll get much more evidence on the importance of turnout over the next few weeks, starting today when Nevada holds its caucuses. In 2012, according to estimates from McDonald, only 1.9 percent of the voting-eligible population — about 33,000 people — participated in the Republican caucuses in Nevada. That’s tiny: About a third of what turnout was in Iowa in 2012 and less than a tenth of what it was in New Hampshire.

DATE STATE TYPE REPUBLICAN TURNOUT (2012) Jan. 3 Iowa Caucus 5.4% Jan. 10 New Hampshire Primary 24.9 Jan. 21 South Carolina Primary 17.6 Jan. 31 Florida Primary 12.8 Feb. 4 Nevada Caucus 1.9 Feb. 4-11 Maine Caucus 0.6 Feb. 7 Colorado Caucus 1.8 Minnesota Caucus 1.3 Feb. 28 Arizona Primary 11.9 Michigan Primary 13.8 Mar. 3 Washington Caucus 1.1 Mar. 6 Alaska Caucus 2.8 Georgia Primary 13.7 Idaho Caucus 4.1 Massachusetts Primary 7.8 North Dakota Caucus 2.2 Ohio Primary 14.1 Oklahoma Primary 10.5 Tennessee Primary 11.7 Vermont Primary 12.4 Virginia Primary 4.6 Mar. 6-10 Wyoming Caucus 0.3 Mar. 10 Kansas Caucus 1.5 Mar. 13 Alabama Primary 17.7 Hawaii Caucus 1.0 Mississippi Primary 13.6 Mar. 20 Illinois Primary 10.5 Mar. 24 Louisiana Primary 5.6 Apr. 3 District of Columbia Primary 1.1 Maryland Primary 6.1 Wisconsin Primary 18.7 Republican turnout varied radically in 2012 Turnout estimates reflect share of voting-eligible population. Source: electproject.org

The reason Nevada is such an interesting test case is because it otherwise looks like a really good state for Trump. Recent Nevada polls have Trump way ahead, with about 40 percent of the vote. Meanwhile, the polling firm Morning Consult, which has been conducting polls throughout the Republican nomination contest, has had Nevada as one of Trump’s best states. He’s polled at 48 percent among respondents in Nevada since the summer, according to Morning Consult, well ahead of his national average of 36 percent and tied for his second-best performance in any state. (Interestingly, the West is generally not a great region for Trump in Morning Consult or other polling. But Nevada — with its glitzy hotels, casinos, East Coast transplants and retiree population — seems to be a big exception.)

But those polls may have trouble identifying the tiny fraction of Nevadans who will show up at the caucuses today. In 2008, a CNN poll released two days before the Nevada caucuses had John McCain winning with 29 percent of the vote, followed by Mike Huckabee at 20 percent and Mitt Romney at 19 percent. The actual results? Romney 51 percent, with McCain in third with just 13 percent (behind Ron Paul and ahead of Huckabee). That’s about the least accurate poll I’ve ever seen. But, with voter participation in Nevada as low as it is, we should be sympathetic to the pollsters; they’re essentially looking for needles in haystacks.

So if Trump gets 40-something percent of the vote in Nevada, in line with the polls, that will be a sign that turnout might not be such a problem for him. Iowa, where the campaigns are much better organized than anywhere else, will appear to be more of a one-off fluke.

If Trump is in the 20s or low 30s instead — and certainly if he loses Nevada — that will suggest there are openings for Cruz and Marco Rubio later in the calendar. Certainly these opportunities would include the other caucus states, but to a lesser extent, they might include other primary states, too, where turnout usually isn’t quite as high as in New Hampshire and South Carolina.

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