This could be the shortest presidential primary ever

New York Yankees great Yogi Berra purportedly once said "it ain't over till it's over" — that an outcome isn't final until a competition's participants have played out the entire contest.

But when it comes to the 2024 Republican presidential nomination race, the end of the road looks to be nearing. Former U.N. Ambassador Nikki Haley has vowed to carry her challenge against former President Donald Trump to her home state of South Carolina, which votes on Feb. 24. Yet her prospects there look poor: Trump leads Haley by more than 30 percentage points in 538's South Carolina polling average. A Trump victory of that magnitude would make it difficult for Haley to continue garnering the financial support needed to keep campaigning — if she even wants to risk further damage to her political stature with sizable defeats in races beyond South Carolina, such as the last February contest, Michigan's primary, on Feb. 27.

Should Haley quit by late February, the 2024 Republican race would rank as the shortest highly contested presidential primary since the modern nomination process took shape in the 1970s. Competitive primaries — even ones involving incumbents — have usually gone through a fair number of elections with multiple active contenders, even when the outcome was no longer in doubt. But Trump's quasi-incumbent status, with his deep hold over the Republican Party, has created the conditions for an unusually brief race. By late February, at most five states (plus the U.S. Virgin Islands) will have cast ballots. This would beat out the current records for the earliest end date (March 3 in the 2004 Democratic contest) and the lowest number of voting states (19 in the 2000 Democratic race).

Measuring the effective end date of the competitive period of a nomination race depends on each cycle's results and how long candidates remain active. Drawing on political scientist Caitlin Jewitt's work on presidential primary competition, we can classify a candidate as their party's presumptive nominee either when all viable opponents have dropped out or when they clinch a delegate majority from the results of primaries and caucuses. Mathematically, Trump can't clinch a delegate majority this year until the March 12 primaries and caucuses, but he could sew up the nomination earlier if Haley were to suspend her campaign before then. In 2004, for instance, Massachusetts Sen. John Kerry became the earliest presumptive nominee in modern times when his last viable opponent, North Carolina Sen. John Edwards, dropped out of the Democratic race on March 3.

A primary's length based on calendar date is something of a moving target. The first contest — traditionally the Iowa caucuses — sometimes happens earlier, sometimes later, while the gap between elections on the primary calendar can vary. The 2024 Republican contest's Jan. 15 start date was on the early side, historically, which has precipitated a potentially quick conclusion in terms of the race's calendar end date.

This year's GOP calendar likely also played a role in reducing the number of contests candidates could remain viable for. Specifically, the first month and change of the Republican contest is unusually devoid of activity, with 41 days stretching from the Iowa caucuses through the South Carolina primary — the longest duration from first to last early states since Nevada became an early-voting state in 2008. As a result, Trump could also become the presumptive nominee despite barely any states having voted. The previous record for fewest contests, the 2000 Democratic race, ended on March 9 when New Jersey Sen. Bill Bradley dropped out after 19 contests had taken place, leaving Vice President Al Gore as the presumptive winner.

Despite that drawn-out early period, the 2024 Republican contest could be the shortest based on the overall length of the primary's competitive period, too, though defining that metric — and which candidates should count as viable — is not an exact science. Based on Jewitt's formulation, the 1992 Democratic contest is currently the shortest ever, having lasted 39 days from Iowa's Feb. 10 caucuses through March 19, when former Massachusetts Sen. Paul Tsongas suspended his campaign and left Arkansas Gov. Bill Clinton as the only viable Democratic contender. But the race technically kept going because a candidate with no chance of winning — former California Gov. Jerry Brown — stayed in to push a reform message on issues like campaign finance. Brown gave Clinton a few scary moments, too, including defeating Clinton in Connecticut's March 24 primary and pushing Clinton in New York's April 7 primary (Clinton finally clinched a delegate majority in early June).

If Haley sticks it out until South Carolina, the 2024 Republican race would last 41 days — a tad longer than that 39-day mark, but also arguably shorter because Brown remained a thorn in Clinton's side beyond it in the 1992 Democratic contest. Despite what Haley says publicly, though, an earlier withdrawal is still a live possibility. Haley is 52 years old and could still have a lengthy political career ahead of her, so she might eventually conclude that continuing could be counterproductive for her future prospects. Some party leaders are calling for her to drop out, and continuing to attack Trump, the party favorite, might hurt her image among influential Republicans as well as voters. Moreover, considering her deficit in South Carolina polls, she might also decide that carrying on isn't worth risking an ugly loss in her home state.

Either way, Trump looks nearly certain to win the GOP nomination — barring something unexpected — as his strength in this primary has been akin to an incumbent president facing a notable primary challenger. Take Trump's showing in New Hampshire. He defeated Haley by 11 points, 54 percent to 43 percent, a margin not too different from that of Jimmy Carter in 1980 (10 points) and George H.W. Bush in 1992 (16 points), sitting presidents who each fended off meaningful challengers. He even did better than some incumbents, like Gerald Ford, who only beat Ronald Reagan by about 1 point in the 1976 GOP contest (Ford was an unusual case, too, having not been elected president or even vice president).

That Trump has the look of a quasi-incumbent makes sense. He's the first former president to make a comeback bid in the modern primary era, unlike past incumbents who lost reelection in that period, such as Carter and George H.W. Bush. Considering 60 percent or more of Republicans have consistently told pollsters that they don't think Trump legitimately lost the 2020 election, it follows that a large swath has shown little inclination to move on from him. Trump's hold over the GOP has also shown through his high favorability ratings among Republicans and a large number of endorsements from Republican elected officials, who've become a Trumpier group since Trump first ran for president. These factors also helped limit the size of the Republican candidate field in 2024 — it peaked at 11 "major" candidates per 538's reckoning, smaller than the 2016 GOP or 2020 Democratic fields — as many presidential aspirants who've aligned themselves with Trump opted not to run against him.

Whether Haley fights on to South Carolina or beyond, Trump looks well positioned to do significantly better in upcoming contests than he did in New Hampshire. The Granite State's primary electorate is comparatively moderate and less religious, thanks to both the state's political makeup and its rules that permit independents to vote in the primary. Tellingly, the New Hampshire exit poll found that about 3 in 4 self-identified Republicans preferred Trump to Haley, while Haley won about 3 in 5 of everyone else. Having that kind of lock on the party base clearly augurs well for Trump in South Carolina, where we can expect the electorate to be more conservative and rock-ribbed Republican. And if Haley can't perform well in her home state, it's even harder to imagine her doing well in the many states that vote on March 5 (Super Tuesday) that also have solidly conservative primary electorates, such as Alabama, Arkansas, North Carolina, Oklahoma, Tennessee and Texas.

All told, a potentially very short Republican primary and President Joe Biden's limited opposition for the Democratic nomination irreducibly point to an especially long general election campaign. That campaign, at least, won't be over until it's over, many months from now.