Alan Wilson, the attorney general of South Carolina, won the state’s Republican primary runoff for governor on Tuesday, according to The Associated Press, just days after President Trump made the unusual move of endorsing both him and his opponent in the contest.

Mr. Wilson, a National Guard veteran, defeated Pamela Evette, the lieutenant governor of South Carolina, who was the first candidate to receive Mr. Trump’s endorsement last month. Even before she secured the president’s backing, Ms. Evette had largely centered her campaign on her loyalty to Mr. Trump.

But the president’s support was not enough to help her avoid a runoff. And last week, as polls showed Mr. Wilson leading Ms. Evette, Mr. Trump announced on Truth Social that he was endorsing both candidates, hedging his bets amid his mixed results with governor’s races this year. The president, who pays close attention to his political standing, wrote on Truth Social that “with either one you can’t go wrong.”

As of Tuesday night, Mr. Wilson had won around 65 percent of the vote. Ms. Evette had about 34 percent. South Carolina has elected only Republican governors since 2002, meaning that Mr. Wilson is likely to become governor in November.

Several factors seemed to work against Ms. Evette leading up to the runoff.

Even as South Carolina voted for Mr. Trump in 2016, 2020 and 2024, and was quick to embrace his MAGA movement a decade ago, voters seemed to sour on Ms. Evette’s all-Trump-all-the-time messaging — expressing more interest in a leader who would focus on steering their fast-growing state through infrastructure troubles and rising costs.

And it did not appear to sit well with voters when Mr. Trump suggested in his endorsement that Ms. Evette recruit the son of Gov. Henry McMaster — who cannot run again because of term limits — as her second in command.

That fueled backlash among Ms. Evette’s opponents, who accused her of negotiating a backroom deal. Ms. Evette denied those claims and said she would not pick her running mate until after the primary. The son, Henry McMaster Jr., later removed himself from consideration.

Mr. Wilson, like the other Republican candidates for governor, also went to extraordinary lengths to gain Mr. Trump’s support. He had a “Trump Tough” section on his campaign website, and he frequently praised the president in speeches.

But he focused his messaging on affordability and amassed significant support from other candidates who failed to make the runoff, including two sitting members of Congress, Representatives Nancy Mace and Ralph Norman.

His ground game was also widely seen as highly effective, with hundreds of volunteers making calls and knocking on doors.

The winner of the runoff will face State Representative Jermaine Johnson, who clinched the Democratic nomination this month.