Nathaniel, I think that another explanation for Haley’s continued presence in the race is less political and more personal. Clearly, the two candidates don’t get along, and never really have. (Remember that the only reason Trump even tapped Haley as ambassador was as a favor to then-Lt. Gov. McMaster.) With the race getting increasingly chippy and personal, I think Haley may be staying in for longer than politically savvy because she knows just how much it gets under Trump’s skin. This is, after all, a politician who sells shirts that say "Go ahead and underestimate me, that’ll be fun."

—Jacob Rubashkin, Inside Elections

It was pretty clear Trump was going to be the nominee after New Hampshire. I think maybe Haley could be forgiven for trying to stay in for a couple more weeks to see if she could move the needle in South Carolina, a state she knows so well. But after it was clear that Trump’s polling lead wasn’t shrinking, she lost any practical justification for staying in the race.

—Nathaniel Rakich, 538

Shortly after quickly being projected the winner, Trump took to the stage and thanked his supporters. He said his victory tonight would be repeated in November, when they'd gather to tell Biden he was fired. Nine months is a long time to wait, he said, and he asked Gov. Henry McMaster, who was on the stage with him, if there was anything he could do to speed it up. "In certain countries, you're allowed to call your election date," he said, and added he would speed it up if he could. Rather than give a long speech himself, though, he shared the stage with McMaster and the states two Senators, Graham and Scott, who both condemned Trump after the Jan. 6 insurrection. Scott was until recently trying to oust Trump as the presumptive nominee, but Trump said he'd done a better job advocating for him than he had for himself. "I'm just very happy he didn’t have that same energy, drive because I probably would have been out of the race a long time ago," Trump said. Scott took to the stage and asked in a country growl, "Is South Carolina Trump country???" fully in campaign mode. The crowd booed Graham, who spoke flatteringly of Trump regardless.

—Monica Potts, 538

Was there any point besides principle in Haley staying in up until tonight? The writing has been on the wall for weeks, and getting trounced in her home state is a humiliation she could have spared herself. This obviously just makes the inevitable even more apparent, but if she didn’t drop out after New Hampshire, what’s a couple more weeks on principle? (Assuming she has enough money to continue campaigning through Super Tuesday, that is.)

—Kaleigh Rogers, 538

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