Darline Graham, the sister of the late Republican senator Lindsey Graham, was sworn in to fill his Senate seat on Tuesday, just three days after his sudden death.

Graham was appointed by Henry McMaster, South Carolina’s governor, to fill the remainder of her brother’s current term.

Graham arrived in the Senate chamber, accompanied by Republican senators Tim Scott, who became the senior senator from South Carolina after her brother’s death, and Katie Britt of Alabama. Senator Chuck Grassley administered the oath of office – Graham placed her hand on a bible and pledged to “support and defend the constitution of the United States against all enemies, foreign and domestic”. When she finished, the chamber erupted in extended applause.

Upon her swearing in, Graham made history as the first woman to represent South Carolina in the Senate.

Lindsey died on Saturday night, aged 71. With the backing of Donald Trump, Darline was swiftly appointed to serve the remaining months of his Senate term, which ends on 3 January.

“Lindsey took care of his little sister in years long departed. It’s my honor to ask his little sister, Darline Graham, to finish his work for him now,” the Republican governor said at a press conference convened at South Carolina’s state capital in Columbia on Monday.

In brief remarks on Monday, Graham said it was an “honor” to stand in as her brother’s replacement.

“I promise to work hard over the next several months to support the president and carry forward the efforts of my brother on behalf of the citizens of South Carolina and the United States,” she said. “I think this is what Lindsey would have wanted, and I plan to honor him in this way.”

At the time of his death, Graham was seeking a fifth Senate term, having won the Republican nomination only last month.The state GOP will hold a separate special election on 11 August to choose a new Senate nominee, who will face off against Democrat Annie Andrews in the November midterms.

Darline has never held public office, but was a steady presence at her brother’s side, supporting his political career as his national profile grew. Since 2019, she has served as commissioner of the South Carolina Commission for the Blind, according to McMaster’s office. Before that, she held positions at Clemson University and in two South Carolina state agencies.