Sen. Lindsey Graham, R-S.C., has unexpectedly died following a "sudden illness," his office said Sunday.

"On the evening of Saturday, July 11, U.S. Senator Lindsey Graham passed away from a brief and sudden illness," Graham's office said in a statement on X.

Graham, a prominent Republican and ally of President Donald Trump, was 71.

"Senator Graham's family appreciates prayers at this time and asks for privacy during this incredibly difficult period," his office added.

Graham had just returned from a trip to Ukraine. A spokeswoman for Graham, when reached by MS NOW, had no additional information on the circumstances of his passing and said more information would become available in the coming days.

Graham had spoken with reporters in Kyiv on Friday, including Ukrainian President Volodymyr Zelenskyy about U.S. sanctions against Russia and Ukraine's air defenses, Reuters reported. Graham recently crossed the aisle to work with Democratic colleagues to update Russia sanctions legislation. In a picture released by Zelenskyy's office accompanying the story, Graham is smiling while standing and shaking hands with the Ukrainian leader.

Graham was a senator for 23 years, having first been elected in 2002. He previously served in the U.S. House, having been elected as part of an influential class of Republicans in 1994. His long tenure gave him seats on powerful committees, most recently chairing the Senate Budget Committee and serving on the Appropriations, Judiciary and Environment and Public Works committees.

He had been running for reelection for a fifth six-year term in a safe Republican seat. Under South Carolina law, South Carolina Gov. Henry McMaster has until Jan. 3, 2027, to fill the seat for Graham's current term. According to South Carolina law, the state must hold an election on Aug. 11 to replace Graham on the ballot. The filing period opens on the second Tuesday after the candidate's death, which would fall on July 21.

McMaster's office didn't immediately respond to a request for comment on filling the seat or on replacing Graham on the November ballot.

Rep. Nancy Mace, who lost her bid for governor in a Republican primary in June, is "strongly considering" running for Graham's Senate seat, according to a person familiar with her thinking.

Graham was scheduled to appear on "Meet the Press" Sunday morning. Host Kristen Welker said in a Facebook post that it would have been Graham's 64th appearance on the NBC show and said Trump and Israeli Prime Minister Benjamin Netanyahu would join instead to reflect on the senator's "life and legacy."

Graham's sudden death leaves Republicans without a crucial vote in the Senate in the months until his seat can be filled. Coupled with Kentucky Republican Sen. Mitch McConnell's extended medical absence, it could hamstring Trump's priorities in the months leading up to the 2026 midterm elections.
Prior to Graham's death, Republicans held a narrow, 53-47 majority.
Trump has led a pressure campaign in recent months to get the Senate to pass a controversial election bill, dubbed the SAVE America Act, that would require photo identification to vote and proof of citizenship to register.
The bill advanced out of the House earlier this year, but has stalled in the Senate. Graham was a co-sponsor of the legislation and a leading advocate for its passage on the Hill. His death complicates an already murky path forward for the election bill.

Graham became a close ally of the president's on the Hill, though he initially resisted Trump's rise.
During the 2016 presidential election, when both men were vying for the Republican nomination, Graham called Trump "unfit for office." Trump, in return, called Graham a "nut job."

"If we nominate Trump, we will get destroyed.......and we will deserve it," Graham wrote on social media on May 3, 2016.
But Graham and Trump repaired their relationship again during Trump's first term and became regular golfing buddies. In recent years, Graham had been a loyal ally of the president, rarely breaking with Trump.
"I said everything," Graham said in a January 2018 interview on CBS News, of his relationship with Trump. "I said he was a xenophobic, race-baiting religious bigot. I ran out of adjectives. Well, the American people spoke, and they rejected my analysis."

Graham later was critical of Trump after the Jan. 6, 2021, attack at the Capitol, carried out by a mob of the president's supporters who believed the election had been stolen. In a floor speech that same day, Graham said President Joe Biden was lawfully elected. But he did not join seven of his Republican colleagues the next month in voting to convict Trump of inciting an insurrection after he'd been impeached by the House.

Trump, in a post on Truth Social, said Graham was "one of the greatest people and Senators I have ever known."

"He was always working, and was a true American Patriot. Lindsey will be greatly missed!!!" Trump wrote.

Graham's unexpected death prompted an outpouring of condolences and remembrances.

Zelenskyy said he was "deeply saddened" by the news of Graham's death.

"He visited Ukraine ten times during the years of Russia's full-scale invasion and was here with our people when it was most needed," Zelenskyy said in a post on X.

Netanyahu said he and his wife Sara were grieving "with the American people over the loss of our dear friend, Senator Lindsey Graham."

"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 post on X.

Senate Majority Leader John Thune, R-S.D., said in a statement: "My heart is heavy this morning to learn of the passing of my friend and colleague, Senator Lindsey Graham."

"He was a strong advocate for the United States and a strong ally to freedom-loving countries across the globe. He believed in the might of America to achieve good in the world and dedicated his life to advancing that cause."

McMaster called Graham "the fiercest of fighters for South Carolina and America—and a loyal and steadfast friend."

And Sen. Tim Scott, South Carolina's other senator and a fellow Republican, said he had "lost a friend."

"Lindsey remained committed to public service and doing what he loved," Scott said in an X post. "He always introduced levity and brought wit to the most challenging moments."

Before being elected to Congress, Graham served in the U.S. Air Force, logging six-and-a-half years of active-duty service as a lawyer.

During the first Gulf War in the early 1990s, Graham was called to active duty and served as a Staff Judge Advocate, where he prepared service members for deployment to the Gulf region.

Graham retired from the Air Force Reserves in June 2015, having served his country in uniform for 33 years. He retired at the rank of Colonel.

A native South Carolinian, Graham grew up in a blue-collar family in the small town of Central, where his parents ran a restaurant and pool hall, according to his website. The first member of his family to go to college, Graham earned his undergraduate and law degrees from the University of South Carolina.

— Emily Wilkins contributed to this report