“Perdue thought that Trump was a magic wand,” said Newt Gingrich, the former House speaker and a Trump ally, who was among Mr. Perdue’s highest-profile Georgia supporters. “In retrospect, it’s hard to understand David’s campaign, and it’s certainly not the campaign those of us who were for him expected.”…

Mr. Perdue’s failures were not just of his own making. He was outflanked by a savvy incumbent in Mr. Kemp who exploited the powers of his office to cut off Mr. Perdue from allies — including Mr. Perdue’s own cousin Sonny, a former governor and Trump agriculture secretary whom Mr. Kemp’s allies appointed chancellor of the University System of Georgia.

Mr. Kemp also appeared to punish those who crossed him: One congressional seat was drawn to exclude the home of a candidate whose father, a Perdue supporter, had publicly criticized the governor.

And he offered goodies to voters, including a gas-tax holiday that conveniently runs through the end of May, just past the primary.