Prominent US Senator Lindsey Graham, a key ally of President Donald Trump, died on Saturday aged 71 following a “brief and sudden illness”, his office said.

Graham, known for his foreign policy work, was a staunch supporter of the US-Israeli war on Iran and in recent years urged both Trump and the Biden administrations to back Kyiv’s fight against Russia’s invasion.

“On the evening of Saturday, July 11, US Senator Lindsey Graham passed away from a brief and sudden illness,” the Republican senator from South Carolina’s office said in a statement on his official X account.

“Senator Graham’s family appreciates prayers at this time and asks for privacy during this incredibly difficult period.”

Trump paid tribute to the influential senator on Sunday, calling him “one of the greatest people” in a post on his Truth Social site.

“Senator Lindsey Graham, one of the greatest people and Senators I have ever known, is dead! He was always working, and was a true American Patriot. Lindsey will be greatly missed!!!”

Graham made a failed bid for the presidency in 2016, warning at the time that Republicans should not back Trump because he was a “race-baiting, xenophobic, religious bigot”.

Their relationship was strained by the Jan 6, 2021 Capitol insurrection, with Graham saying his Republican colleagues should “count me out, enough is enough” — although he later voted against convicting Trump in his impeachment trial.

Graham reconciled their relationship after Trump returned to office and supported his re-election bid.

‘A great friend of Israel’

Graham was also a strong supporter of Israel and a hawkish backer of the US-Israeli war on Iran.

Israeli Prime Minister Benjamin Netanyahu said: “Lindsey is a great friend of Israel and a cherished friend of mine.”

“Lindsey understood that the security of Israel and America are inseparable. He devoted his life to defending America, strengthening our alliance and standing up for the free world,” Netanyahu said in a statement released by his office.

Israeli President Isaac Herzog said the news left him “shocked and heartbroken”. “Senator Graham was a beacon of moral clarity and a true leader of the US-Israel partnership,” he said in a post on X.

“We will never forget how he stood by the people of Israel in our most difficult moments, and we will remain eternally grateful for his sense of justice, truth, and loyalty,” Herzog said.

During the US-Israeli war on Iran, Graham has called for regime change in Iran, warned Saudi Arabia of “consequences” if it does not take military action against Tehran, and brazenly lauded US strikes on Iran.

In May, he urged Arab and Muslim nations to join the Abraham Accords as part of the Iran peace deal, warning of “severe repercussions for our future relationships” with those countries if they did not.

Graham’s death comes as the weeks-long hospitalisation of former Republican Senate leader Mitch McConnell rattles the party over the final months of his long congressional career.

Republicans hold a narrow 53-47 majority in the Senate, but will have little room for missing votes or defections. McConnell was admitted to hospital last month and has not voted since June 11.

Graham was first elected to the US House of Representatives in 1994, before being elected to the Senate in 2002.

He was later re-elected to the Senate in 2008, 2014 and 2020 and most recently served as chairman of the Senate Budget Committee.

Graham served as a military lawyer and attained the rank of air force colonel, an experience that informed his interventionist stance in foreign policy.

In 2002, he voted in favour of military action against Iraq in the wake of the September 11 attacks, and later supported a long-term US presence in Afghanistan.

Graham was a frequent critic of former president Barack Obama’s foreign policy, calling him a “weak opponent of evil” in 2015 over his negotiation of a nuclear deal with Iran.