Former Pentagon official Katie Arrington announced Tuesday she is running against fellow Republican Rep. Nancy Mace of South Carolina. On Wednesday, Arrington snagged former President Trump’s blessing. Trump described Mace, the first-term incumbent, as “an absolutely terrible candidate .. whose remarks and attitude have been devastating for her community, and not at all representative of the Republican Party to which she has been very disloyal.”

Mace responded by appearing outside Trump Tower and reminding South Carolinians that the last time Arrington was the GOP nominee, a Democrat ended up winning the seat. “If you want to lose this seat once again in midterm election cycle to Democrats, then my opponent is more than qualified to do just that,” she said.

That’s essentially going to be the debate in a primary that will serve as a test of Trump’s influence over the base. The former president’s Election Day endorsement of Arrington in 2018 led to the primary race defeat of then-incumbent GOP Rep. Mark Sanford, affectionately dubbed “Mr. Argentina” by Trump in reference to his high-profile extramarital affair while serving as governor. Like Mace, Sanford was a quietly libertarianish Republican with an independent streak.

“Attitude,” as Trump says, is a big part of the argument against Mace, too. While her voting record is mostly conservative, she is more media-friendly and less in-your-face than is currently fashionable in her party. It’s also possible to get to her right on hot-button social issues, though this, combined with her opposition to offshore drilling (Arrington supports it) are arguably assets in this district.

The case against Arrington is based on a quality Trump usually disdains: She lost her last general election. But she did so under a set of circumstances unlikely to be replicated this cycle: an automobile accident that kept her off the campaign trail, a bad year for Republicans, and a Democrat who could siphon off the less Trumpy parts of the GOP coalition. 

Arrington’s counterargument will be that Trump won the district by 6 points to Mace’s 1.2, and the GOP will need MAGA enthusiasm to drive turnout. A lot may ride on whether that contention is true — Mace’s flavor of conservatism may be a better local fit. Can Trump overcome that, as he did against Sanford, and hope a red wave carries Arrington to Capitol Hill? Stay tuned.