For the purposes of this analysis, I think we should view Trump as an incumbent when measuring his performance in the primary. Republican voters know exactly what Trump is like in the White House, and they can judge for themselves how he did on the issues they care about (he generally does well on this axis) and his character (things are more muddled here).

If we think of him as an incumbent, he is doing quite poorly. Remember how Pat Buchanan embarrassed H.W. Bush by getting 38 percent of the vote in New Hampshire in 1992 and is blamed for weakening him for the general? Haley has been doing better than Buchanan across the early states. There are plenty of Republican voters who don't think of Trump as ideal. We've probably all heard their arguments. Something along the line of, "his character isn't ideal, but he fights for me."

Now, what does this all mean for the contest against Biden in the fall? Not much. The vast majority of those people will vote for Trump in the fall. And if we are sticking with the 1992 comparison, Bill Clinton was a popular candidate (net +11 favorability in September of '92). Joe Biden is not. His favorability rating is currently at net -15 points. So, Trump is doing poorly, but so is Biden. When it's a race to the bottom all around, doing poorly in a GOP primary doesn't tell us all that much.

—Galen Druke, 538

I see your point, Mary — Trump has gotten “only” around 50-60 percent in the first three contested states — but I think in the grand scheme of things, that’s still a strong performance. Iowa winners much more often finish in the 20s or 30s, and New Hampshire is just weird because of its demographics and high proportion of independent voters. And at the end of the day, he’s the first non-incumbent Republican to win all three of Iowa, New Hampshire and South Carolina, and there’s a good chance he’s going to win all 56 contests.

—Nathaniel Rakich, 538

For a non-incumbent (if former president), Trump has made short work of the primary calendar, basically annihilating any real competitors in record time without ever having to deign to step foot on a debate stage. The fact that he didn’t completely cruise to the nomination captures some of the hesitancy in the party that Julia highlighted, but at the end of the day, all Trump needs to do now is be more popular than Biden, who isn’t exactly the Prom King these days.

—Kaleigh Rogers, 538

I'm honestly not sure there is a clear way to go about establishing what Trump "should" be winning, Mary. On the one hand, polls had him at 61 percent, so 60 percent of the vote (as of now) is pretty good — especially if you consider he'll win the nomination easily by mid-March if this is the case.

Another benchmark would be the percent of the GOP electorate that calls themselves "part of the MAGA movement." According to preliminary ABC exit polls, that's about 44 percent of SC voters (50 percent said no and 6 percent were unsure). So by this benchmark, Trump is actually overperforming.

Too bad there aren't a whole lot of modern examples of former presidents + failed presidential candidates running in subsequent primaries, or else we could try to establish historical baselines. Trump's performance right now is somewhere between George H.W. Bush vs. Pat Buchanan and Jimmy Carter vs. Ted Kennedy. Both of those incumbents lost in the general.

—G. Elliott Morris, 538

As of 9:20 p.m., 70 percent of the expected vote is reporting in South Carolina, and Trump is leading Haley by 20 points. It’s a decisive victory for the former president, as expected, though a somewhat smaller margin than his average lead in the polls heading into today (around 28 points).

Haley’s margin of defeat, though, looks even larger when it comes to delegates: Under South Carolina’s delegate allocation system, over half the state’s 50 delegates are awarded to the statewide winner, while the rest are awarded by congressional district. It looks like the maximum delegates Haley could walk away with in her home state tonight is three, if she holds onto her lead in the 1st District.

Despite this, Haley proclaimed in her speech that tonight’s result demonstrated her home state’s frustration with the country’s direction and reiterated her promise to stay in the race.

And on that note ... We hope to see you back here for our Super Tuesday live blog on March 5! We're gearing up for an eventful night tracking not only the presidential race in 15 states (and one territory) but a slew of down-ballot primaries in Senate, House and gubernatorial races as well.

—Tia Yang, 538