South Carolina voters are heading to the polls in a runoff election to permanently fill the Senate seat left vacant by the death of Lindsey Graham, with his sister Darline Graham, who was appointed to the seat temporarily and is backed by President Trump, facing Republican Congressman Ralph Norman. The contest is being closely watched as a test of Trump's influence over the party, with several Republicans privately doubting Graham can win despite his endorsement, given her limited experience in elected office and a widely criticised debate performance in which she admitted being "not informed" on national security.

Polling from the Trafalgar Group put the two candidates level at 48% each, within a 2.9-point margin of error, while early voting turnout and straw polls were reported to favour Norman. Trump has campaigned in person and virtually for Graham, including a rally in Myrtle Beach, and South Carolina's senior senator Tim Scott has also backed her, saying he waited nearly a month before endorsing to be sure she was ready. Graham has sought to present herself as a public servant rather than a career politician, leaning on Trump's endorsement and traditional GOP values, though her policy record remains thin after being thrust unexpectedly into mourning, governing and campaigning within the space of a month.