The sister of the late Lindsey Graham has been sworn in to take his seat in the Senate.

Darline Graham Nordone wiped away tears after visiting her brother's desk cloaked in a black drape before the ceremony in a somber moment on Tuesday.

Her time the Senate floor was brief, as she was sworn in by Senator Chuck Grassley of Iowa to fill the remainder of her brother's term as South Carolina senator. Graham died suddenly aged 71 on Saturday.

The Republican's longtime friend and Nordone's new fellow senator from South Carolina, Tim Scott, stood by her side as she took the oath. She did not address the chamber after being sworn in.

Although appointing family members to fill the seat of a deceased loved one is not uncommon, Nordone, 62, is the first ever sibling to take office in this manner.

All other previous appointments have been either spouses or children.

Her new Republican colleague, Senator Lisa Murkowski of Alaska, was appointed by her father Frank Murkowski, after he resigned and ran for governor.

House Republican Julia Letlow, who is the GOP nominee for US Senate in Louisiana this year, took over the seat of her late husband Luke in a special election after he passed away from COVID in 2021 before he could be sworn in to the office. 

With support of President Donald Trump, South Carolina Republican Governor Henry McMaster appointed Nordone to finish out Graham's term, which expires in January. 

To fill the seat permanently, the Republicans have a primary scheduled for August 11. That contest will advance to a runoff on August 25 if no single candidate wins a majority of votes. 

Graham's sister told reporters that it was 'a privilege' to help finish Graham's 'important work.'

'My brother was the most amazing person, outstanding leader, and just a genuinely good man,' she said.

'I think this is what Lindsey would have wanted, and I plan to honor him in this way.'

President Trump commended the decision to pick Nordone, saying the appointment is a 'fabulous tribute to Lindsey, who loved her dearly.'

Nordone and Graham enjoyed a close relationship. He adopted her at the age of 22 when she was just 13, after the passing of both of their parents. She has never served in public office before.

The siblings grew up sharing a single room behind the Sanitary Cafe, the bar, pool hall, and liquor store their parents ran on Main Street in the small town of Central, South Carolina.

The family later moved into a trailer and then a house next door to the bar.

Nordone leaned on her big brother long before they were orphaned, running to him whenever she was sick or stuck on her homework.

He taught her to ride a bike, sprinting alongside and shouting encouragement, and picked her up when she fell.

'He's kind of like a brother, a father and a mother rolled into one,' she told the New York Times in 2015.

Their mother died of Hodgkin's lymphoma in 1976, and a heart attack claimed their father a little more than a year later.

Nordone moved in with an aunt and uncle while Graham finished his studies at the University of South Carolina.

He gave up his weekends to travel home and care for her while his classmates stayed on campus to enjoy themselves.

He then enlisted in the Air Force, where his guardianship of Nordone allowed her to qualify for his benefits, and she has credited him with getting her through high school and on to college.

She went on to become a mother of two and built a career helping people with disabilities find work, a success her brother wore as a badge of honor.

'Of all the things that have happened in my life, her turning out so well is the highlight of it by far,' Graham told C-SPAN in 2015.

Nordone introduced him on stage when he launched his White House bid in their hometown in 2015.

'Lindsey was always my parent,' she said at the time. 'There was no doubt in my mind or anyone else's mind that Lindsey was my guardian.'

The vacancy for South Carolina's Senate seat was created by Graham's unexpected death, which was announced just after 2am Eastern time Sunday morning.

Per a statement issued by his office just before 5pm that day, 'aortic dissection due to arteriosclerotic cardiovascular disease,' was the cause of death.

'The death certificate will be PENDING until all the toxicological and microscopic testing are finalized, and at that point the death certificate will be updated to reflect the cause of death and appropriately classify the manner of death,' Graham's spokesman added.

A 911 call for 'cardiac arrest' was placed from Graham's residence around 8.30pm on Saturday evening.