Iowa Lesson Looms Over South Carolina Primary as Trump Endorsement Faces New Test

South Carolina voters head to the polls Tuesday to pick nominees for governor and other key offices, in what amounts to the latest measure of President Donald Trump's influence over Republican voters. But if Iowa's recent gubernatorial primary proved anything, Trump's backing is powerful but never a sure bet.

Iowa's Warning Shot for the Trump Endorsement

Trump recently endorsed South Carolina Lieutenant Governor Pamela Evette to succeed term-limited Republican Governor Henry McMaster. It is a high-profile nod in a state Trump carried comfortably in three presidential runs, never dipping below 55% of the vote. Yet Iowa Republicans already demonstrated that a Trump endorsement does not automatically translate into victory.

In Iowa's own Republican gubernatorial primary, Trump's chosen candidate, U.S. Representative Randy Feenstra, narrowly lost to businessman Zach Lahn. That result sent a clear message to conservative voters nationwide: endorsements carry weight, but grassroots energy and candidate quality still matter at the ballot box.

Crowded GOP Field Vies for McMaster's Seat

Seven Republicans are competing to replace McMaster, who is term-limited after a decade in office. Evette has the advantage of both Trump's and McMaster's endorsements, a formidable combination in a deeply red state.

However, the field includes serious challengers. U.S. Representative Nancy Mace, a onetime steadfast Trump ally who later broke with the president over releasing the Jeffrey Epstein files, still prominently touts a past Trump endorsement on her campaign website. U.S. Representative Ralph Norman and state Attorney General Alan Wilson, son of Congressman Joe Wilson, round out the major Republican contenders.

Regardless of who wins, the next governor will play a pivotal role in the early stages of the 2028 presidential race. South Carolina is expected to again host the critical first-in-the-South presidential primaries, keeping the state at the center of national politics.

Graham Seeks Fifth Term with Trump's Backing

U.S. Senator Lindsey Graham faces five Republican primary challengers in his pursuit of a fifth term. Graham also carries Trump's endorsement into the primary, along with a massive financial advantage.

Graham had spent over $29 million on his reelection bid as of May 20, dwarfing every Republican and Democratic challenger. He entered the final stretch with roughly $4.2 million remaining, more than double the rest of the GOP field combined. That kind of war chest makes him the clear frontrunner, though Iowa's results show money and endorsements alone do not always close the deal.

On the Democratic side, physician Annie Andrews, who previously challenged Mace for her House seat in 2022, is among those vying for the nomination.

Open House Seat Draws Crowded Ballot

Mace's decision to run for governor leaves her 1st Congressional District seat open. Eleven Republicans and seven Democrats will appear on primary ballots, though former Governor Mark Sanford has dropped out of the Republican race.

None of South Carolina's seven congressional seats are expected to be particularly competitive in November. Those districts were at the center of a mid-decade redistricting effort backed by Trump to eliminate the state's sole Democratic-held seat. The Republican-controlled state Senate ultimately rejected that effort, and candidates are running under the current map.

What to Watch on Election Night

Primary winners must secure a majority of the vote to avoid a June 23 runoff between the top two finishers. With crowded fields in both the gubernatorial and congressional races, runoffs are a real possibility.

Greenville, Horry, Charleston, Richland, and Spartanburg counties are the most populous and will play significant roles in both party primaries. Large counties with significant Black populations, such as Richland, Florence, and Sumter, tend to carry more weight in Democratic contests.

Key data points to monitor as results come in:

• Polls close at 7 p.m. ET.
• South Carolina does not register voters by party, meaning any registered voter can participate in either primary.
• As of Friday, roughly 3.4 million voters were registered statewide.
• About 279,000 ballots had already been cast as of Friday, nearly all from early in-person voting.
• In 2022, about 29% of Democratic primary votes and 17% of Republican primary votes were cast before election day.

Nearly all of South Carolina's 46 counties release their early voting results in the first vote report of the night, typically before posting any election day totals. In the 2022 primary, the AP first reported results at 7:21 p.m. ET and had counted 99.9% of votes by 1:14 a.m. ET.

Recounts are automatically triggered if the margin between candidates is 1% or less of the total vote. The AP will only declare a winner when it determines no scenario exists for a trailing candidate to close the gap.

Why Iowa Voters Should Pay Attention

While South Carolina is over 800 miles from Iowa, Tuesday's results carry real implications for the Hawkeye State. The early 2028 presidential landscape will be shaped by governors and election officials in key primary states. How Trump's endorsement performs in South Carolina will also shape strategy for conservative candidates across the country, including those eyeing future races in Iowa.

Iowa Republicans already proved that voters will make their own decisions. South Carolina may reinforce that lesson, or it may show that Trump's endorsement still carries the day in the right circumstances. Either way, the results will offer a preview of the forces shaping the next presidential cycle.

As of Tuesday, there are 14 days until the June 23 primary runoff and 147 days until the November 3 general election.