I think you're both right, Nathaniel and Kaleigh, that there's no way Haley can win. She might just be staying in to prove a point and rally the non-Trump base to her side, to take a stand she can point to as prescient if Trump loses. But I think the big issue that she and most other Republicans have been dancing around is the four court cases around the country Trump is facing, his age and a range of any number of unexpected things that could happen between now and November. I think Haley might stay in the race in case something like a criminal conviction, a kind of deus ex machina for the primary that changes the story, without her having to really go after and fight Trump. The truth is he has a lot of potential weaknesses as a potential candidate, no matter how slim the potential for him to be actually sent to prison before November is. Maybe she's trying to position herself as the natural alternative should one of those things happen.

—Monica Potts, 538

Look, Haley is going to lose out to Trump for the Republican nomination. That's been apparent really before we even had votes to count, although it was right to see what actual voters would do in the early contests. But if Haley wants to risk what remains of her political career pushing back against Trump and what he means to the party she's dedicated her political life to, we shouldn't rule out that having longer-term practical implications and influence on voters. Acquiescing to Trump has been a pretty regular thing among Republicans since the 2016 election, but carrying a torch for an alternate vision is something Haley may be inclined to do, to hell with the consequences. Granted, the realities of continuing a campaign with less and less money coming in could end this race pretty soon, but we'll just have to see what she decides to do.

—Geoffrey Skelley, 538

To Jacob's point, the "go ahead and underestimate me" phrase is a very clearly gendered one. And Trump's reputation on this issue hasn't gotten as much attention as it did in 2016, but it's not clear that some of the issues have gone away. Plus, Haley may also be highlighting the fact that, as far as she is from being a real contender for the nomination, this is the closest any GOP woman has come.

—Julia Azari, 538 contributor

People forget this, but McMaster was the first statewide elected official to endorse Trump back in 2016. Haley’s appointment to U.N. ambassador cleared the way for him to become governor, a post he still holds today.

—Nathaniel Rakich, 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