Incumbent Darline Graham (R) and Ralph Norman (R) are running in a special Republican Party primary runoff on August 25, 2026, in South Carolina to determine which candidate will be the Republican nominee in the state's general election on November 3, 2026. In the primary, Graham received 33% of the vote to Norman's 24%.

The special primary became necessary after incumbent Lindsey Graham (R), the Republican nominee selected at the June 9 primary, died on July 11, 2026.

This is the first runoff for a U.S. Senate election in the state since 2004. Since 1956, only two people — Strom Thurmond (R-S.C.) and Lindsey Graham (R-S.C.) — had been elected to this Senate seat. President Donald Trump (R) won the state in 2024 with 58% of the vote. Graham won re-election in 2020 with 54% of the vote. Republicans have won the state in every presidential election since 1980, every Senate election since 2004, and every gubernatorial election since 2002.

South Carolina Daily Gazette's Seanna Adcox wrote, "The runoff pits a 62-year-old first-time candidate against a 73-year-old congressman who's held elected office since 2004."

Darline Graham was appointed to complete the term of her brother, Lindsay Graham. After the initial primary, she said, "I decided to answer the call to serve because South Carolina and President Trump need a leader who is taught, principled and will fight to advance our conservative values in Washington." President Donald Trump (R) and Sen. Tim Scott (R) endorsed Graham.

Ralph Norman has represented the state's 5th Congressional District since 2017. He finished in third place for the Republican nomination for governor. In a TV advertisement, he said, "South Carolina needs a proven conservative with a record of fighting for you. You shouldn't have to guess where your next senator stands: With me, you already know." Former Gov. Nikki Haley (R) and Rep. Nancy Mace (R), who finished fifth place in the nomination for governor, endorsed Norman.

Axios' Natalie Daher wrote, "The runoff will offer a revealing test of Trump's influence over a Republican electorate in which nearly every major candidate supports his agenda." In June, Trump endorsed Lt Gov. Pamela Evette (R) for governor before later issuing a dual endorsement for Evette and Alan Wilson (R). Wilson defeated Evette 68%-32% in the June 23 runoff.

In 2026, Trump has had a 96% overall primary endorsement success rate, tied with 2024 for the second-lowest percentage, and behind only the 2022 election cycle with 93% success. To read more about Trump's endorsements, click here.

The Republican nominee selected in this special primary will become the 29th replacement nominee for a U.S. Senate candidate since 1918. To read more about replacement nominees in U.S. Senate contests, click here.

Thirty-three of the 100 U.S. Senate seats are up for election, and another two seats are up for special election. Democrats hold 13 of the seats up for election, and Republicans hold 22. As of April 2026, 11 members of the U.S. Senate announced they are not running for re-election. To read more about the U.S. Senate elections taking place this year, click here.