According to the District of Columbia medical examiner, the rupture was probably due to atherosclerosis.
The news of his death came suddenly on Sunday. As recently as Friday, the senator met with Ukrainian President Volodymyr Zelensky in Kyiv.
71-year-old Graham was originally a Republican of the conservative, traditional wing and criticized Donald Trump harshly before the 2016 presidential election, but later became staunchly loyal.
On Truth Social, Trump wrote on Sunday that Graham was "one of the best people and senators I have ever known."
