We expect Iowa Republicans to have a very white, fairly religious and relatively conservative electorate. To start with, the state is very white. Among the 50 states, Iowa has the sixth-largest non-Hispanic white population share (84 percent). White voters make up a large part of the Republican base nationally, and as Iowa is whiter than most places, the GOP ends up having an almost entirely white electorate there: In 2016, for instance, the National Election Pool entrance poll found that 97 percent of Republican caucusgoers identified that way.

White evangelical Christians will also play a big part in the caucuses. After all, at least 56 percent of the electorate identified as such in the 2008, 2012 and 2016 GOP caucuses, per the entrance polls. Iowa's population as a whole is 19 percent white evangelical Protestant, according to the Public Religion Research Institute, which places it a bit above the national share of 14 percent. But white evangelical Christians are among the Americans most likely to identify as Republican, so we'd naturally expect them to be a more significant force in a GOP nomination contest. (We do have to be wary about the term "evangelical," which has become more inextricably linked to politics at the expense of its religious meaning.)

Lastly, there's good reason to expect a fairly conservative electorate. In 2016, the entrance poll found slightly more participants identified as "somewhat conservative" than "very conservative" — 45 percent to 40 percent — but more voters said they were very conservative in 2008 and 2012. In all three years, no more than 15 percent identified as "moderate." And generally, low-turnout caucuses tend to have more ideologically extreme participants than primaries.

This is in no small part due to higher barriers to participation. Only voters registered as Republicans can participate in party caucuses, which are a time-consuming, one-time event — unlike primaries where voters have all day to cast a ballot (and usually some option to vote by mail). In 2016, a combined 16 percent of Iowa's voting-eligible population took part in the Democratic and Republican caucuses, according to the U.S. Elections Project. This marked the highest turnout for any state using caucuses, but that figure was lower than the turnout in any state that held both a Democratic and Republican primary. Ultimately, the caucus system results in a low-turnout nominating event that magnifies the involvement of the party's most committed members.

If you're looking for a wild card that could shake up the Iowa caucuses, check the weather. Iowa has experienced a succession of brutal winter storms including heavy snow, high winds and seriously cold temperatures over the past week. The low for tonight in Des Moines is forecast to be -8 degrees (without wind chill).

I spent last week on the ground in the state, and if you're tempted to reply, "It's Iowa, they're used to this," allow me to disabuse you of that idea. The state was largely shut down over the weekend. Canceled flights, no campaign stops, many roads were undrivable and people were advised to stay indoors. The National Weather Service noted that weather of this type is experienced just once or twice per decade. All of this is to say, after hunkering down for days and now facing arctic temperatures, don't be surprised if some Iowans who'd planned to caucus stay home tonight.

There's some debate over how low turnout could affect who shows up to the caucuses. On one hand, Trump supporters register as more enthusiastic than those of other candidates. On the other hand, Trump's supporters tend to be more marginal voters who don't vote as regularly as some other parts of the electorate. He does disproportionately well among people who say they plan to caucus for the first time, a group that may also be the first to say, "actually, I'm not braving the cold to spend hours in a high school gymnasium." On top of that, Trump's supporters also tend to be more rural, which may mean having to confront less-navigable roads.

So keep all that in mind as the results come in and pour out a hot cuppa for the Iowans venturing out in the cold tonight.

Earlier this month, Haley caught some flack for seeming to disparage the ability of Iowans to pick presidents, joking on the campaign trail that while "Iowa starts it, [New Hampshire] corrects it."

While Haley's remark might cost her politically — DeSantis brought it up multiple times in last week's debate and featured it in his closing Iowa ad — she isn't exactly wrong about Iowa's track record, especially in recent years. It's been over two decades since the winner of a contested Iowa caucus has gone on to win the GOP nomination and the presidency. That was George W. Bush, who won 41 percent of the caucus vote in 2000. Since then, no Iowa caucus winner has won the GOP nomination, let alone the White House. Mike Huckabee in 2008, Rick Santorum in 2012 and Ted Cruz in 2016 were all the runners-up in their respective primary races despite making an early splash in Iowa. Overall, in the eight contested Iowa Republican caucuses since 1976, the winners have only gone on to claim the nomination three times.

The state is actually far better at picking Democratic nominees: 2020 was the first time since 1992 that the winner of the caucus (either Pete Buttigieg or Bernie Sanders) didn't go on to win the nomination. Of course, that track record wasn't enough to convince the party to keep Iowa as the first-in-the-nation contest this year.

Good evening, folks! I'm Jacob Rubashkin, and I'm the deputy editor of Inside Elections, a nonpartisan newsletter in D.C. that does news and analysis of House, Senate and gubernatorial elections across the country. At Inside Elections, we keep track of every single competitive federal race in the country and use that detailed coverage to project how each party will perform in November. I'm also a contributor at 538 and have been doing these liveblogs for a few years.

Tonight, I'll be watching a few things: First, whether Trump crosses 50 percent, which is about where he's currently polling in Iowa (52.7 percent to be exact); second, who wins second place (because if DeSantis comes in third, he should be on dropout watch); and third, whether Ramaswamy pulls a Pete Buttigieg and surprises us all. I'm not saying he'll win or even come close, but will his ferocious pace of campaigning push him above his 6.4 percent polling average?

Trump gave a victory speech to supporters in Iowa at about 10:30 p.m., and spent an uncharacteristically long time talking about other people. He thanked his supporters, his family, and even his opponents. It took several minutes for him to pivot to his target for the night: Biden, and, in doing so, he picked up the mantle of presumptive nominee.

Here, he listed some of the themes of his campaign, immigration and increasing energy production. He borrowed a phrase from former vice presidential candidate and Alaska Gov. Sarah Palin and said, "Drill, baby, drill." (He even made a joke about electric vehicles.) In talking about immigration he repeated a number of falsehoods about a border that's out of control and immigrants coming in from "insane asylums," echoing some of the themes from his 2016 campaign launch.

In truth, Biden has ramped up deportations, deporting more families and children than Trump did in his last year in office. But border crossings have surged regardless, Republican voters care a lot about immigration, and voters trust Republicans more on the issue. In a reversal of 2020, Trump is poised to be a challenger instead of an incumbent president in this round, and he's already throwing punches.
—Monica Potts, 538