It’s hard to tell when a Trump threat is idle and when it’s real. Part of it depends on how close the election is. That Graham wasn’t up until 2020 gave him the space to rebuild his relationship. When Trump attacked former South Carolina representative Mark Sanford on the day of the Republican primary contest in the state, though, there wasn’t anything Sanford could do about it.
Sanford lost, but it’s not clear what role if any Trump’s tweet might have played. In fact, it’s not clear how much weight Trump’s endorsements have overall, much less how much they’ll carry once he’s out of office and, to at least some extent, the public eye.
While Trump likes to brag about how he can get people elected, that was more true in Republican primaries during his presidency than in contests against Democrats. Data from Ballotpedia show that Trump-endorsed candidates won about 86 percent of their primary contests and 69 percent of their general election match-ups.