At a campaign rally in Michigan a few weeks before she dropped out of the presidential race, Nikki Haley warned the frontrunner in the Republican primary.

“He’s not going to get the 40 percent if he’s going and calling out my supporters and saying they’re barred permanently from MAGA,” she vowed. “He’s not going to get the 40 percent by calling them names. He’s not going to get the 40 percent by trying to take over the RNC.”

Haley had plucked the “40 percent” figure from the results of South Carolina’s primary, where she received almost precisely that share of the vote. To hear her tell it, you would think that number represented the percentage of Republican voters who are reluctant to vote for Donald Trump again but might be persuaded to do so if he changes his approach.

It was a shrewd talking point. It just wasn’t true. The South Carolina GOP had held an “open” primary in which Democrats and independents were free to vote. Because their own party’s presidential primary this year was effectively uncontested, many left-leaning voters seized the opportunity to cast a Republican ballot instead.