Today’s special election GOP runoff for Senate in South Carolina between appointed Sen. Darline Graham and five-term Rep. Ralph Norman (R-SC) will be a clear test over just how much juice President Donald Trump’s endorsement carries within the Republican Party, at a time when his overall political standing has been on the decline. 

Graham has struggled through the shortened campaign to fill the seat of her late brother, dodging the media spotlight (unlike her brother) and sticking to generic talking points in talking about the issues. She faced blowback after admitting she didn’t know enough about foreign policy to answer a debate question about Taiwan — underscoring how much of a novice she is on an issue that defined Lindsey Graham’s legacy. 

But Trump has been a loyal backer, holding a rally last Friday for her campaign, which featured appearances from the state’s Republican leadership, including Gov. Henry McMaster and Sen. Tim Scott (R-SC), who is also the chairman of the National Republican Senatorial Committee. 

Norman also hardly fits the profile of the up-and-coming challenger. He’s 73 and would be one of the oldest freshman senators in recent memory. And for more-moderate Republicans, his record of antagonism towards House Republican leadership and support for declaring martial law in the days leading up to President Joe Biden’s 2021 inauguration make him a deeply flawed choice. 

For national security hawks, Norman’s votes against several Israel aid packages and opposition to Ukraine assistance are also some notable red flags that make Darline Graham the candidate more aligned with her brother’s worldview. 

Trump’s endorsement record has been mixed this year, initially backing the losing gubernatorial candidate (Lt. Gov. Pamela Evette) in South Carolina — while endorsing unsuccessful candidates for governor in Georgia, Iowa, Minnesota and Wyoming. All told, he’s backed 10 unsuccessful candidates in primaries this cycle. But the president’s record in Senate races this year is still perfect, having successfully backed insurgent challengers to Sens. Bill Cassidy (R-LA) and John Cornyn (R-TX). 

In fact, only three of Trump’s Senate endorsees throughout his political career have lost in primaries (Alabama GOP Sen. Luther Strange in 2017; West Virginia Senate candidate Evan Jenkins in 2018; Utah Senate candidate Trent Staggs in 2024).  

Graham is hoping to avoid joining that club, and despite her flubs, she’s still got a strong chance of prevailing. She won the first round of balloting with 33% of the vote — eight points ahead of Norman — and finished a respectable second place in the northeastern corner of the state that makes up Rep. Russell Fry’s (R-SC) home base. (Fry endorsed Graham’s candidacy after finishing in third place in the primary.)

But if Graham falls short, it would not just be a sign that South Carolina voters were wary of her policy inexperience. It would be an indication that the Trump endorsement, while still valuable in Republican primaries, isn’t the automatic ticket to victory that it was for so long.