Donald Trump has recommended Lindsey Graham’s sister be named as the senator’s temporary replacement following his death.

The 71-year-old’s death was announced after a “sudden illness” which sparked an FBI investigation, according to its director Kash Patel.

On Monday, Trump posted on social media that Darline Graham Nordone should be appointed to fulfil the rest of her sibling’s term which expires in January.

The US President said the temporary appointment would serve as a “fabulous tribute” to Mr Graham.

He wrote: “I recommended, to Governor Henry McMaster, Lindsey Graham’s wonderful sister, Darline, to serve as interim Senator from the Great State of South Carolina.

“This would be a fabulous tribute to Lindsey, who loved her dearly!””

The office for Governor McMaster has announced that he will hold a press conference on Monday afternoon local time, to announce who he is selecting to fill the remainder of the term.

Mr Graham, who had served as the senator for South Carolina since 2002, was running for reelection this year.

He had been a long-term Trump ally, despite breaking with the President on some issues including foreign policy.

Shortly after his death was announced, Trump called Graham “one of the greatest people and senators I have known” and a hard-working patriot

Confirming that the FBI’s subsequent probe into his death, Mr Patel wrote on X: “Senator Lindsey Graham was a devoted public servant, a fierce defender of our nation, and a true patriot who dedicated his life to the people of South Carolina and the United States.

“Our prayers are with his family, loved ones, colleagues, and all those who knew him during this devastating time.

“The FBI is assisting local authorities and has made every necessary resource available.”

The chief medical examiner of Washington, D.C. preliminarily said Graham died of aortic dissection due to arteriosclerotic cardiovascular disease.

NBC News said emergency personnel had responded to a call for cardiac arrest at his Capitol Hill home on Saturday night.

Graham, who had served as the senator for South Carolina since 2002, was running for reelection this year and as a frequent visitor to Ukraine, also previous met with President Volodymyr Zelenskiy in Kyiv.

They discussed Ukraine’s air defence ​needs and a Russian sanctions bill, Zelenskiy said.Graham said bolstering Ukraine’s military capabilities and aligning ​sanctions with a diplomatic push could force Moscow into talks.

“The road to ending this ⁠war, the road to peace, passes through Beijing more than it does (through) Washington, Kyiv, or Moscow,” Mr Graham told ​reporters at Kyiv’s Mykhailivska Square.

“China has ​an oversized influence. I’d like them to use their influence for the good of the world.”