U.S. Sen. Lindsey Graham, the influential Republican who transformed from one of Donald Trump's fiercest critics into one of his staunchest allies, has died at age 71.

The South Carolina lawmaker died after a "brief and sudden illness," his office posted on X early Sunday.

U.S. media said emergency personnel had responded to a call for cardiac arrest at ​his ⁠Capitol Hill home Saturday night.

Graham, just back from a trip to Ukraine, had been scheduled to appear on the "Meet the Press” interview program 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.