Trump's endorsement power faces key test in South Carolina, Oklahoma runoffs

President Donald Trump's influence over the Republican Party is on the line Tuesday as voters head to the polls in high-stakes runoff elections in South Carolina and Oklahoma. The results will signal whether Trump's endorsements remain the gold standard in GOP primaries, or whether local dynamics can override presidential backing.

In South Carolina, Trump is backing Sen. Darline Graham in the Republican Senate nomination runoff to succeed her late brother, Sen. Jim Graham, who died unexpectedly this summer at age 71. In Oklahoma, the president supports former state budget secretary Mike Mazzei for the GOP gubernatorial nomination, a race left open by term-limited Gov. Kevin Stitt.

Both contests come after a cycle where Trump's endorsement record has shown cracks. Five of his gubernatorial picks in Republican primaries have already fallen short, including Iowa Rep. Randy Feenstra, who lost his nominating contest this spring. That Iowa connection gives Tuesday's results added relevance for Hawkeye State voters watching how Trump's political capital holds up in the heartland.

What is at stake in the South Carolina Senate runoff?

Darline Graham faces conservative Rep. Ralph Norman in a contest that will determine the GOP Senate nominee on the midterm ballot in reliably red South Carolina. Graham and Norman finished first and second in a special Senate primary two weeks ago, but neither secured a majority, forcing Tuesday's runoff.

Trump made the stakes clear Friday when he headlined a rally for Graham in Myrtle Beach.

We need every South Carolina patriot to go to the polls and vote for Darline Graham. What I really want you to do is pretend, please, that I'm on the ballot. Just come and vote. It's so important.

Graham has the backing of term-limited Gov. Henry McMaster, who appointed her to fill her late brother's Senate seat, as well as Rep. Russell Fry, a top Trump ally, and Sen. Lindsey Graham, South Carolina's senior senator and chair of the National Republican Senatorial Committee.

Norman, who unsuccessfully ran for governor earlier this year, has questioned Trump's decision to back Graham while simultaneously showcasing his own support for the president. He recently picked up an endorsement from former Gov. Mark Sanford, a fiscal conservative who briefly challenged Trump in the 2020 presidential primary.

Norman also has the backing of former Gov. Nikki Haley, who served as Trump's ambassador to the United Nations. Norman was the only member of South Carolina's congressional delegation, and the first House Freedom Caucus member, to endorse Haley over Trump in the 2024 presidential primaries.

Why the Oklahoma governor race matters

In Oklahoma, Mazzei finished slightly behind state Attorney General Gentner Drummond in the initial June GOP primary. A crowded field kept both from winning outright, sending the race to Tuesday's runoff. The winner will be considered the clear general election favorite in the Republican-dominated state.

Trump has touted his endorsement record this cycle, posting over the weekend that his endorsements are stronger than ever. But the losses have mounted. Beyond Iowa's Feenstra, Trump-backed candidates who fell short include Georgia Lt. Gov. Burt Jones, Wyoming Superintendent Megan Degenfelder, and Minnesota businessman Mike Lindell.

What does this mean for Trump's political influence?

The South Carolina race has become something of a referendum on Trump's political power, according to one South Carolina-based Republican consultant who spoke with Fox News Digital on condition of anonymity.

It's becoming a referendum on Trump. He came to South Carolina to solidify his endorsement because he has to show a win here.

Veteran GOP strategist Ryan Williams offered a more measured view.

There's no question that an endorsement from President Trump provides a tremendous boost in a Republican primary. But it doesn't necessarily mean the candidate's going to win. The president still has a firm grip on the party, even in places where a candidate he backed loses a nomination. But if there are underlying issues with a candidacy, those can pose problems that even an endorsement can't overcome.

Georgia special election runoff adds to Tuesday's stakes

Tuesday also features a special election runoff in Georgia to fill a congressional seat left vacant after Democratic Rep. David Scott's death in April. Both finalists are Democrats: former Gwinnett County School Board Chair Everton Blair and Marcye Scott, the late congressman's daughter. The winner will further reduce an already fragile Republican House majority.

What should Iowa voters watch for?

For Iowans, the runoffs offer a preview of how Trump's endorsement power will factor into future primary contests, including those in the Hawkeye State. Feenstra's loss this spring showed that even presidential backing does not guarantee victory in a Republican primary. Tuesday's results will show whether that trend continues or whether Trump reasserts his dominance.

The races also highlight the ongoing tension between establishment Republican figures and grassroots conservative activists, a dynamic that plays out in Iowa caucuses and primaries as well. Voters watching from Iowa can gauge whether Trump's brand remains strong enough to sway contested primaries or whether local candidates can overcome presidential opposition with strong grassroots support.

Polls closed in South Carolina at 7 p.m. Eastern, with results expected later Tuesday evening. Oklahoma polls close at 8 p.m. Eastern.