Republican Senator Lindsey Graham, a close ally of US President Donald Trump, has died at the age of 71. He died on Saturday evening following a “brief and sudden illness”, according to his office.

Elected to the Senate in 2002, the South Carolina politician was one of Washington’s most influential voices on foreign policy, often pushing for US military intervention overseas.

Donald Trump said Graham was a “true American Patriot” who would be “greatly missed”.

Graham had just returned from Kyiv, where he met Ukrainian President Volodymyr Zelensky on Friday. There were no known health concerns ahead of his trip.

Trump told NBC News that he had spoken with Graham hours before his death and the senator “sounded great” but a little tired.

“He was a tough cookie in many ways,” Trump told NBC on Sunday. “If he wanted to get something, if he thought he was right and he had people against him, he could be very tough, actually. But he was a good person.”

According to US media, emergency personnel responded to reports of a cardiac arrest at a house owned by Graham in Washington DC on Saturday night.

Graham was previously a vocal critic of Donald Trump, calling him a “race-baiting, xenophobic, religious bigot” in 2015. The next year, ahead of the 2016 presidential election, he said: “If we nominate Trump, we will get destroyed… and we will deserve it.”

After the US Capitol riots in 2021, Graham told the Senate: “Trump and I, we’ve had a hell of a journey. I hate it to end this way.

“All I can say is a count me out. Enough is enough.”

But over time his tone towards the president softened.

He voted against convicting Trump in the 2021 impeachment trial, and supported his election in 2024.

Graham cited Trump’s record on the US southern border, the killing of Iran’s powerful military commander Qasem Soleimani and the appointment of conservative judges.

“There is a dark side to Donald Trump… and he was a very good president. But I am sticking with him because I saw what he did,” Graham told the BBC in 2023.

Graham was known for his interventionist stance on foreign policy, including strong support for Israel and the war in Iran.

He told CBS last month that the US would “obliterate” Iran if the country did not submit to US control of the Strait of Hormuz. It was one of his last televised interviews.

Israel’s Prime Minister Benjamin Netanyahu said on Sunday that “Lindsey understood that the security of Israel and America are inseparable”.

Israel lost “one of its greatest friends”, he added.

Graham also voted in favour of military action against Iraq in the wake of the September 11 attacks in 2001 and was opposed to the withdrawal of US troops from Afghanistan in 2021, describing it as a “sad and dangerous event for US national security”.

“Jihadists all over the world are celebrating,” he added. “America will be seen as weak.”

The senator was also a stalwart supporter of arming Kyiv and applying sanctions against Moscow. Zelensky said in a post on X, external that he was “deeply saddened” by his death.

“America and the world have lost a determined leader,” he added.

South Carolina Governor Henry McMaster now has the power to appoint a temporary replacement for Graham until the end of his current term in January.

His successor will be chosen in November’s midterm elections.

Before Graham’s death, Republicans held a 53-47 majority over Democrats in the Senate. Both parties are fighting for Senate control in November.

The death comes as another Republican senator has been hospitalised for weeks with an unknown medical condition. Aides to Kentucky Senator Mitch McConnell have released few details about his condition.