There was a moment in early 2023 when Donald Trump seemed like a politician in decline.

And it wasn’t just his political opponents who thought so. National Republicans, who blamed Mr. Trump for the party’s run of bad results in the midterms, largely agreed.

But now it’s starting to set in: It appears the former president’s staying power was underestimated … again. Mr. Trump is the overwhelming favorite to be the Republican presidential nominee — and his supporters remain the most influential force in the party’s politics.

This week, through conversations at an event with South Carolina Republicans, we try to understand why the party continues to back an embattled Mr. Trump — and how it came to feel as though this primary ended before it even began. Then, Astead talks with Jonathan Swan, a New York Times political reporter, about how the Trump team has approached this campaign with discipline and strategy, and what it is planning should he win back the White House.