In a February poll from Suffolk University/USA Today, likely South Carolina GOP primary voters were asked the most important issue facing the country. Of the options offered, 42 percent said that “immigration and border security” is the most important issue, 26 percent said “the economy” and 13 percent said the “future of American democracy.” No other issue offered got more than 5 percent of respondents.

—Mary Radcliffe, 538

The Republican presidential primary started out in territory pretty friendly to Haley. That changes after today, making the South Carolina primary a sort of last chance for the former Palmetto State governor to prove she actually has a path to the 1,215 delegates necessary to secure the GOP nomination. It looks somewhere between unlikely and impossible that she'll be able to pull that off.

It's all about the numbers. According to the polls, Trump leads Haley by about 30 points among likely Republican primary voters. But his delegate lead is what really matters — and it's likely to be even larger. That's because the South Carolina Republican Party awards its delegates on a winner-takes-all basis. About half the delegates will go to the winner of the statewide vote (almost certainly Trump) and the remainder will go to the winner of each of the state's seven congressional districts. With a 30-point statewide victory, Trump would probably win every district resoundingly; in 2016, the largest difference between Trump's statewide margin (10 points) and his margin in the most anti-Trump county (which he lost by 5 points to Marco Rubio) was only 15 points.

This is all disastrous news for Haley, who needs all 50 delegates from the state to be on track to win the Republican nomination. The competition on and after Super Tuesday will be even tougher. According to the math powering 538's delegate benchmarks, Trump is leading Haley by around 57 points in California and 69 in Texas, the states with the largest delegate hauls on Super Tuesday. Those states also allocate delegates on a winner-takes-all basis, as long as a candidate wins at least 50 percent of the vote.

The primary, in other words, is functionally over. But because Trump has not yet clinched a majority of delegates, Haley's campaign technically has a chance of winning. It's just very, very low.

—G. Elliott Morris, 538

In the debut poll from The Citadel School of Humanities and Social Sciences, 69 percent of likely South Carolina GOP primary voters said they expected Trump to win the primary by a large margin — which would line up with his average polling lead of nearly 30 points. Nine percent said they thought Trump would win in a close election, 10 percent thought Haley would win in a close election and only 2 percent said they thought Haley would win by a large margin. Voters who told the pollster they plan to vote for Trump were especially confident: 89 percent said they thought the former president would win by a large margin, compared to 33 percent of Haley voters.

—Mary Radcliffe, 538

If you're not quite as election-obsessed as us here at 538, please allow me (a person who willfully chose to spend an evening three weeks into her maternity leave watching the GOP debate) to fill you in on the last few weeks.

At the start of the year, there were still six major candidates competing for the Republican Party nomination. By the end of January, only two remained. In Iowa, Trump came out on top with 51 percent of the vote, followed by DeSantis and Haley. Ramaswamy and Hutchinson both dropped out after the Iowa caucuses (Christie dropped out just before), while DeSantis ended his campaign just before the New Hampshire primary, where Trump defeated Haley 54 percent to 43 percent.

So far, though, Haley has refused to throw in the towel, despite trailing Trump badly in polls.

She also did poorly in two additional contests in early February. In Nevada, where Trump wasn't even on the primary ballot (he was on the ballot for the Nevada GOP caucus … it was a whole thing), she still got only 31 percent, with voters preferring the electoral equivalent of "none of the above." And she lagged behind Trump in the Virgin Islands GOP caucuses, too.

I'll have more in a bit about why Haley might still be running, but suffice to say it's an uphill battle against the former president.

—Kaleigh Rogers, 538