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On Friday, Donald Trump made a rare appearance at a political rally in Myrtle Beach, South Carolina, on behalf of Darline Graham, telling voters to pretend he was on the ballot when they voted. On Tuesday, they listened.

Graham entered politics just six weeks ago, when she was appointed to fill the Senate seat vacated by the sudden death of her brother, Lindsey Graham. At first, she was a placeholder, but then she decided to run for a full term for the seat with Trump’s backing. The race immediately became a test of whether Trump’s backing could help Graham, a political neophyte known to voters only because of her last name, win a primary election in the deep-red state.

It turns out he could. On Tuesday, Graham pulled out a victory in the Senate runoff over Rep. Ralph Norman by a margin of 52.5 percent to 47.5 percent, making her the Republican nominee for Senate and the overwhelming favorite to secure a six-year term in November.

As Graham herself admitted in her election-night victory speech, directly addressing the president via the medium of cable television, “Our victory would not have been possible without you, and we are truly grateful. South Carolina is truly Trump country.”

She wasn’t merely flattering the president. Graham’s victory can be credited to the massive margins she ran up in the Pee Dee, the region of the state around Myrtle Beach where Trump campaigned for her. His rally appearance, along with the endorsement of local Rep. Russell Fry, who was the third-place finisher in the first round of voting two weeks ago, transformed that region into a stronghold for Graham. Darline Graham got a higher percentage of the vote in the area than her late brother did when he won his primary in June, shortly before his death, in........

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