Senator Lindsey Graham of South Carolina died Saturday night after a “brief and sudden illness,” his office announced. President Donald Trump, who spoke with Graham shortly before his death, noted on Sunday that the senator had returned from a trip to Ukraine and seemed tired but that such fatigue was understandable. Trump added that Graham had been eager to continue working on a voter ID bill. Graham, a close Trump ally despite early opposition, was a prominent Republican voice on foreign policy, and leaders including Ukraine’s president offered tributes. The cause of death was not specified beyond the illness, though emergency crews responded to a cardiac arrest call at his Washington home.