What’s At Stake In The South Carolina Republican Primary

We’ve been inundated with polls: South Carolina polls, Nevada polls, national polls, general election polls. In fact, there are so many polls that you can tell yourself pretty much any story you like about the Republican presidential primary. Is Ted Cruz surging? There’s a poll for that. Is Cruz stalling out? There’s a poll for that too. Have you heard about the poll showing a Ben Carson comeback? OK, I made that one up. But earlier this week, you could find a poll with John Kasich in second place in South Carolina, even though he was polling at about 2 percent there earlier this month.

If this were a general election, we’d just say “take the average” and be done with it. That’s still pretty good advice. The average lets us say, with a high degree of confidence, that Donald Trump is ahead in South Carolina. (That part’s easy: Trump has led in all but one poll there since July.) With a slightly lesser but still high degree of confidence we can say that Marco Rubio has gained ground: He was at 13.1 percent in our South Carolina polling average before Iowa1 and is at 16.8 percent now. We can also say that Trump has probably lost a couple of percentage points, but probably not more. We can say that Jeb Bush’s numbers are flatter than the places listed here.

But unlike in the general election, where the polling average usually gives you a fairly precise estimate of where the race will end up, the South Carolina polls could still wind up being way off. We warned you about this before Iowa, where the polls mispredicted the order of finish, and likewise before New Hampshire, where they were closer to the mark (although hardly perfect). We’re probably going to have to keep warning you until the Republican race settles down to only two or three major candidates — multiway races are historically associated with much larger polling errors.

So instead of pretending we know exactly how things will turn out, let’s look at the most likely range of outcomes for each candidate as defined by our polls-plus forecast and consider how those outcomes might affect the race going forward.

Donald Trump

90th percentile forecast: 42 percent
10th percentile forecast: 22 percent

Trump is a heavy favorite in South Carolina. He has a 78 percent chance of winning the state according to polls-plus and an 83 percent chance by our simpler polls-only model — although he’s not quite completely safe. In fact, it’s not that hard to imagine the scenario in which Trump loses: Suppose that this week’s NBC/Marist poll had the race pegged correctly, with Cruz within striking distance, and that Trump fares poorly among late-deciders, as was true in Iowa.2 That NBC/Marist poll sure looks a lot like the pre-Iowa polling average, doesn’t it? Additionally, maybe Trump’s comments about the pope will hurt him?

Fortunately for Trump, the NBC/Marist poll is an outlier relative to the prevailing trend. More likely, Trump will win South Carolina, but the share of the vote he secures while doing so is important. Why did Trump get 35 percent of the vote in New Hampshire but only 24 percent in Iowa? Was it because Iowa is a caucus and New Hampshire a primary? Is it that New Hampshire is in the Northeast and Iowa is in the Midwest? (The Northeast and the South seem to be stronger regions for Trump than the Midwest or the West.) We’ll get more data about that in South Carolina. Perhaps the single most important question in the Republican race is how high Trump’s ceiling is and whether he can eventually get to 50+ percent of the GOP electorate. If Trump wins South Carolina with, say, 41 percent of the vote, he’ll be much closer to that majority than if he limps through to a victory with 26 percent instead.

Ted Cruz

90th percentile forecast: 28 percent
10th percentile forecast: 12 percent

It can be a dangerous game to predict in which direction the polls might be off. But for Cruz, I’d probably take the “over” on 19 percent, his standing in our current polling average. The reason is simply that South Carolina’s evangelical-heavy demographics are not that different from Iowa’s, where Cruz won with 28 percent of the vote. Even if you knock off a few points for Cruz’s “ground game” being less helpful to him in a primary than a caucus, it shouldn’t be a stretch for him to wind up in the low 20s.

And yet, maybe some things have changed since Iowa. Cruz’s favorability ratings, which until recently were among the best in the GOP field, have begun to fray as he’s come under attack more often both from other candidates and from Republican Party “elites.” Cruz’s colleagues don’t like the guy — he has no endorsements yet from his fellow senators — and maybe he isn’t wearing well with Republican voters either.

I also believe that Cruz doesn’t have much of a shot at the nomination unless he finishes toward the higher end of his range. Cruz is at a delegate-math disadvantage in the primaries: Most of the states where he should be strong divide their delegates fairly proportionately, whereas the coastal and northerly states that vote later are winner-take-all or winner-take-most. If Cruz can’t get out to a pretty big delegate lead after Super Tuesday, it’s going to be hard for him to catch up later. And if he can’t win South Carolina or at least come pretty close, it’s hard to see him doing all that well in other Southern states on Super Tuesday.

Marco Rubio

90th percentile forecast: 27 percent
10th percentile forecast: 12 percent

Rubio is nearly tied with Cruz for second place in the polls-plus forecast, but that’s because polls-plus gives Rubio some credit for his growing lead in endorsements — including the backing of South Carolina Gov. Nikki Haley. In the polls-only forecast, by contrast, Cruz is a couple of percentage points ahead of Rubio.

I’m sweating the details on this one because the national media seems to have a hyperbolic reaction to all things Rubio, alternatively declaring him to be on the verge of a breakout or predicting his imminent demise, as they did after New Hampshire. Rubio, who is acceptable to many Republicans but impassions few of them, may be more susceptible to actual or perceived momentum than a love-him-or-hate-him candidate like Trump.

Rubio’s playing a long game, however. Even under the best of circumstances, he’s likely to lose most of the Super Tuesday states to Trump or Cruz. Even under the worst of circumstances, Republicans may come back around to Rubio by process of elimination. That endorsers such as Haley threw their support to Rubio even after his New Hampshire debacle is partly a reflection of Rubio’s resilience — he was reasonably good in last week’s debate, and his polls have held up pretty well — but also an indictment of Bush, Kasich and the other alternatives.

So I’ll be looking to two benchmarks for Rubio. One is whether he approaches 20 percent of the vote; as The New York Times’ Nate Cohn points out, that’s a key threshold for Rubio because many Super Tuesday states use 20 percent as a minimum threshold for awarding delegates. The other, more obvious one is how Rubio fares relative to Bush. Let’s talk about Jeb!

Jeb Bush

90th percentile forecast: 19 percent
10th percentile forecast: 6 percent

I thought Bush was effective in the last couple of debates. His ground game was surprisingly impressive when we visited Iowa. Bush and his super PAC are still dropping more money than any other candidate: In South Carolina, the Right to Rise PAC backing Bush had spent roughly $13 million on ads through Feb. 14 according to data from Kantar Media/CMAG, almost as much as all other Republican candidates and super PACs combined (about$17 million).

So the fact that Bush performed so poorly in Iowa and New Hampshire (don’t give me any spin about his having “beaten expectations”) — and that his numbers have been so flat in South Carolina despite the spending, the debates and the Bush family jamboree would seem to suggest that Republican voters simply aren’t buying what he’s selling.

Frankly, this has seemed apparent to us for a long time. Nonetheless, I’ll keep an open mind about Bush until we get this last bit of evidence, which is how he fares among South Carolina voters. The thing about the primaries is that they can string candidates along. If Bush can spin some kind of narrative about South Carolina to his donors, welp, it’s only three more days until Nevada and then just seven more days until Super Tuesday and then just another week until Michigan and then just a week more until Florida votes on March 15. Even if Bush is a zombie candidate, his presence in the race makes it hard for the field to consolidate.

There’s also an outside chance that Bush could do legitimately well in South Carolina instead of just muddling through. Some state polls have had Bush in the mid-teens, and our polls-plus model gives him a 27 percent chance of finishing in the top three and even an outside chance of a second-place finish. Personally, I don’t see a Bush second place happening. But one advantage of a statistical model is that it can force you to consider possibilities you might otherwise be too dismissive of.

CANDIDATE 1ST 2ND 3RD 4TH 5TH 6TH
Donald Trump 78% 15% 5% 1% <1% <1%
Ted Cruz 11 38 30 13 5 3
Marco Rubio 10 35 33 15 6 2
Jeb Bush 1 8 18 32 24 17
John Kasich <1 3 11 24 34 27
Ben Carson <1 1 5 14 30 50
Chance of finishing in each position, S.C. GOP primary

Percentages displayed are from FiveThirtyEight’s polls-plus forecast

John Kasich

90th percentile forecast: 16 percent
10th percentile forecast: 5 percent

Kasich has gotten a pretty sizable post-New Hampshire bounce. He’s gained about 6 percentage points in South Carolina polls since New Hampshire, according to our polling average, and also several points in national polls. The problem is that Kasich was starting out at about 2 percent in both cases, so even a fairly large bounce doesn’t really put him on the radar. Kasich doesn’t have a lot on the line in South Carolina — in fact, he’ll abandon the state as votes roll in Saturday to campaign in the Republican stronghold of Massachusetts3 — but his best scenario is that he beats Bush while Rubio also fares poorly.

Ben Carson

90th percentile forecast: 13 percent
10th percentile forecast: 3 percent

Speaking of zombie campaigns, Ben Carson is still running for president! And his presence matters a little more than you might think. A fraction of Carson’s roughly 7 percent of the vote could be the difference between Cruz winning states on Super Tuesday and losing them to Trump, or between Rubio hitting delegate thresholds and failing to do so. If you’re the sort of weirdo who loves these details, you’re in luck: We’ll be live-blogging South Carolina and the Nevada Democratic caucuses all day4 Saturday, and we hope you’ll join us.

Check our our live coverage and results from the South Carolina Republican primary.

Footnotes

1. Annoyingly, there weren’t any South Carolina polls conducted between Iowa and New Hampshire.
2. And to a lesser extent, in New Hampshire.
3. To be fair, Massachusetts holds its primary on March 1.
4. The Nevada Democratic caucuses begin at 11 a.m. Pacific time Saturday. Based on Nevada’s historical speed at counting votes, we expect to have the final results in no later than August.

Nate Silver is the founder and editor in chief of FiveThirtyEight.