President Donald Trump has reportedly been musing over his own mortality since the death of his friend and fellow Republican Lindsey Graham.In public and private, Trump, 80, has said he was shocked by Graham’s sudden death on July 11. But those close to the president emphasized that Trump has been rattled by the death of a close ally, nearly 10 years younger, according to the Washington Post.“I said ‘You guys, I just can’t believe it,’” Trump told NBC News’s “Meet the Press” on July 12, describing his feelings after learning Graham had died. In another interview with “Fox & Friends” on July 13, Trump reiterated that Graham was a “workaholic” and “just didn’t stop.”Trump is expected to attend Graham’s funeral this afternoon and later lead a tribute to the former South Carolina senator at the Washington National Cathedral.While speaking about his friend and lawmaker Lindsey Graham, President Trump has marveled at how energetic Graham was shortly before his death (AP)Graham died earlier this month from an aorta tear in his heart – likely caused by the hardening of arteries, a medical examiner said. Graham was just returning to the United States from a visit in Ukraine when it occurred. Trump has said he was speaking with Graham on the phone, just hours before the 71-year-old senator died. “I don’t feel great. He was a great guy. He was a friend. He would call me all the time. I’d say ‘stop calling me Lindsey.’ It just – he was amazing,” Trump told “Fox & Friends.”In interviews, the president has repeatedly highlighted how hard-working and energetic Graham was, emphasizing how unexpected Graham’s death was.