Mathematically, Trump can't clinch a delegate majority until the March 12 primaries and caucuses, but he could sew up the nomination earlier if Haley were to suspend her campaign before then. With Haley staring down a potentially sizable defeat in South Carolina, it's possible she could drop out shortly after today's contest. If she did, the 2024 Republican race would rank as the shortest competitive presidential primary since the modern nomination process took shape in the 1970s.
As of today's contest, only four states (plus the U.S. Virgin Islands) have cast ballots. The race ending today — or even after Michigan's primary next week — 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).
An unusually drawn out early voting period likely played a role in winnowing the number of contests candidates could remain viable for: The period from Iowa through South Carolina lasted 41 days, the longest duration from first to last early states since Nevada became an early-voting state in 2008. As a result, Trump could become the presumptive nominee earlier than ever by calendar date and despite barely any states having voted.
Despite that drawn-out early period, the 2024 GOP primary could also be the shortest by the number of days in its competitive period, although that's up for debate. Based on political scientist Caitlin Jewitt's formulation, the 1992 Democratic contest is the shortest ever, having lasted 39 days until 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. If Haley drops out tonight, the 2024 Republican race would last 41 days — a tad longer than the 39-day mark, but also arguably shorter because Brown remained a thorn in Clinton's side beyond it in 1992.
—Geoffrey Skelley, 538