It's not a huge surprise that Haley thinks she can win tonight despite the odds. Her first political success was in a 2004 South Carolina state House Republican primary, in which she unseated a powerful 30-year incumbent to win. She tells that story on the stump, and the message is clear: She's won as an underdog before.

As a legislator, Haley carved out a reputation in South Carolina as an outsider taking on state power. She sponsored a bill to force roll call votes on issues like raising legislator pay, losing support from her colleagues and a race for a committee chair position in the process. Later, as governor, she became known for luring businesses to the state, siding with business over labor, signing a 20-week abortion ban and blocking Medicaid expansion.

On social issues, though, she has tried to walk a middle path. Haley has talked about the racism her Indian American family faced in rural South Carolina, and supporters have said the "good ol' boys" network never quite accepted her in state politics. But she also frames her success as an example of how the South has made progress. She didn't tackle the issue of the Confederate battle flag flying over the State House until after a racist shooting in Charleston in 2015, in which nine churchgoers were killed in Emanuel AME Church. She has also sidestepped more recent controversies, like anti-transgender bathroom laws.

Of course, all of her history in the state hasn't seemed to help her against Trump. In polls, she's winning only about a third of potential voters. She may be used to playing the role of David, but not all Goliaths fall in defeat.

—Monica Potts, 538

If you are looking for something to listen to while we wait for polls to close and results to come in, allow me to suggest our latest episode of the 538 Politics podcast. We talk about what to expect tonight, including how South Carolina's primary electorate is different from that of other early states and how the results might shape what Haley does next. We also had a debate about a recent poll on presidential greatness and looked at polling that suggests the wars in Ukraine and Gaza have created some significant divides within the two parties.

—Galen Druke, 538

Let's not sugar-coat this: If the polls are right, Haley will lose badly to Trump in South Carolina, her home state, tonight. According to 538's average of polls, Trump commands the support of 62 percent of likely primary voters compared with Haley's 34 percent. Haley has gained ground in recent weeks, likely a result of voter consolidation as the rest of the candidates dropped out after voting in Iowa and New Hampshire, but so has Trump.

Moreover, according to a poll released this week by Suffolk University/USA Today (which had a very similar breakdown to our average), Trump is leading Haley with most major demographics in the state. The former president leads among Republicans and conservatives, groups that make up 76 and 81 percent of Republican primary voters in the state, respectively. Haley, meanwhile, holds an almost 20-point lead among respondents who described themselves as moderate or liberal and a 26-point lead among those who say the most important issue is the future of democracy.

According to my colleague Geoffrey Skelley, if Trump wins by as much as the polls imply, it would be the best-ever performance for a non-incumbent presidential candidate in South Carolina primary history. (The current record is George H.W. Bush's 28-point win over Bob Dole in 1988.) Surely the Haley campaign will try to spin a victory out of defeat — Trump is no easy opponent, to be fair — but with these numbers there's simply no denying Trump's strength.

—G. Elliott Morris, 538

Polls are open in the Palmetto State, the latest battleground in the GOP presidential primary race. You'd be justified in asking if this will also be the contest's last battleground, as Trump's commanding lead in the polls suggests he'll almost certainly walk away with all the delegates tonight and continue his march to the nomination. We'll certainly be looking out for Haley to signal what she'll do next: She's insisted that she plans to stay in the race, but a big home-state loss could throw cold water on an already-struggling campaign.

As for the timing of it all, polls will close at 7 p.m. Eastern, and we wouldn't be surprised if a winner is projected not long after. As usual, though, we plan to stick around to analyze results and candidate speeches throughout the evening. We'll also discuss how Trump got to be the overwhelming favorite on Haley's home turf, whether there are any upsides for Haley as the last challenger standing and (gulp) what it all means as we turn toward November's general election.

—Tia Yang, 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