U.S. Senator Lindsey Graham, a South Carolina Republican who evolved from a sharp critic of Donald Trump into one of his most trusted allies, died Saturday evening at age 71. His office said he died following a "brief and sudden illness."

Graham's communications director confirmed the news in a statement posted to social media early Sunday, saying the senator's family was asking for privacy during a difficult time as they process the loss. No official cause of death has been released, though an emergency call recording from Saturday night referenced a dispatch for cardiac arrest at a residence belonging to the senator, and photos reviewed by NBC News showed paramedics removing a person on a stretcher from his home.

First elected to the Senate in 2002, Graham built a political career defined by his shifting relationship with Trump, moving from critic to one of the president's closest advisers on Capitol Hill, while remaining a persistent voice for American intervention abroad, often diverging from the isolationist wing of Trump's base. He chaired the Senate Budget Committee and had also led the Judiciary Committee, and was in the midst of campaigning for a fifth term this November after clearing multiple primary challengers in June.

Graham was in Ukraine as recently as Friday, where he met with President Volodymyr Zelenskyy, part of what Zelenskyy described as ten wartime visits to the country. The Ukrainian leader said in a statement that Graham had been a genuine defender of freedom and of the values underpinning global security. Graham was also known as one of the Senate's most outspoken defense hawks on Iran and a leading advocate for continued U.S. support of Israel.

Tributes poured in from across the political spectrum. President Trump, writing on Truth Social, called Graham one of the greatest people and senators he had known, describing him as a true American patriot. Senate Majority Leader John Thune praised him as a strong advocate for the United States and a reliable ally to freedom-loving nations worldwide. Israeli Prime Minister Benjamin Netanyahu said in a statement that Israel had lost one of its greatest friends and that he personally had lost a beloved friend. Even in Iran, state media reported on the senator's death, characterizing him as both a war hawk and a longtime adversary of the Iranian government.

Under South Carolina law, Governor Henry McMaster will appoint a replacement to serve out Graham's term until January, while state law appears to call for a special primary on August 11, with a possible runoff on August 25, to select a new Republican nominee for the November general election. Graham's death also comes amid health concerns for fellow Republican Sen. Mitch McConnell, who remains hospitalized after a reported cardiac emergency last month.