UPDATE: Trump remembers Sen. Graham as 'unique in every way'

The South Carolina lawmaker died after a "brief and sudden illness," his office posted on social media. U.S. media said emergency personnel responded to a call for cardiac arrest Saturday night at his Capitol Hill home in Washington.

The DC medical examiner preliminarily ruled the cause of death as aortic dissection due to arteriosclerotic cardiovascular disease, Graham's office said Sunday afternoon. That's when the inner lining of the body's main artery tears and blood leaks out, according to the Mayo Clinic.

The contest to succeed Graham will not impact the broader fight for control of the Senate in November between Republicans and Democrats, as South Carolina is a reliably Republican state.

However, his death robs Trump of a dependable Senate vote as the president seeks to push his agenda in the closely divided Senate.

"He's a tough one to lose," Trump told NBC's "Meet the Press" program. "He was great. He was unique in every way."

Another senior Republican in the upper chamber — Sen. Mitch McConnell of Kentucky — remains hospitalized for undisclosed health problems, and said in a statement Sunday that he will not return to the Senate yet.

Speaking on CNN's "State of the Union" program, Trump said Graham, who had just returned from a trip to Ukraine, called him on Saturday night. "Other than being tired, he was fine," Trump said.

The president said he received news of Graham's death early Sunday morning.

Under South Carolina law, the state's Republican governor, Henry McMaster, can immediately appoint a temporary replacement to fill Graham's seat.

South Carolina Republicans must then also hold an expedited primary election to pick a nominee for the November midterm election. That nominee does not have to be the same person McMaster picks as a temporary replacement.

Graham, a defense hawk, was a prominent supporter of Israel and Ukraine and an opponent of Iran.

He was scheduled to appear on "Meet the Press" on Sunday morning, the network said.

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

Ukrainian President Volodymyr Zelenskyy said he was "deeply saddened" by the news, calling Graham "a true defender of freedom and the values that make our world safer."

Israeli Prime Minister Benjamin Netanyahu said in a statement: "Israel has lost one of its greatest friends. America has lost a great patriot. I have lost a beloved friend."

Netanyahu expects to attend Graham's funeral, a senior Israeli official said.

During the 2016 presidential campaign, in which Graham was among many Republicans who lost the nomination to Trump, he posted on social media: "If we nominate Trump, we will get destroyed … and we will deserve it."

Graham told CNN in 2015 that Trump was "a race-baiting, xenophobic, religious bigot," adding, "He doesn't represent my party. He doesn't represent the values that the men and women who wear the uniform are fighting for."

Later, after becoming a loyal supporter and frequent golf partner, Graham still publicly disagreed with Trump's decision upon returning to office last year to pardon about 1,500 of the president's supporters who attacked the U.S. Capitol on Jan. 6, 2021, saying it could lead to more violence.

"They did not always agree, but they always agreed to disagree without being disagreeable. … They figured out how to have a friendship," Graham's Republican colleague from South Carolina, Sen. Tim Scott, told "Meet the Press."

On Friday, Graham met Zelenskyy in Kyiv, and the Ukrainian leader said the two discussed Ukraine's air defense ​needs and a Russia sanctions bill.

Graham said China could ​play a decisive role in pressuring Russia toward peace talks, helping end its war in ‌Ukraine.

"The road to ending this ⁠war, the road to peace, passes through Beijing more than it does (through) Washington, Kyiv or Moscow," 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."

"I don't believe (Russian President Vladimir) Putin is there yet, but it wouldn't take much to get him there."

Zelenskyy noted that Graham visited Ukraine 10 times since Russia's full-scale invasion in 2022.

In a Facebook post, Zelenskyy wrote: "We will always be especially grateful for the recognition of our people and words of admiration for the courage of Ukraine's defenders."

Graham recently served as chairman of the Senate Budget Committee and was a member of the Committee on Appropriations, the Judiciary Committee and the Committee on Environment and Public Works.

A former Air Force lawyer and member of the South Carolina Air National Guard, Graham was elected to the Senate in 2002. Before that, he was elected to the House of Representatives in 1994.

He never married and lived in Seneca, South Carolina.