It is a morbid element of journalistic paranoia, only inflamed in the past four years. Macabre and inhuman as it might sound, every foreign correspondent in the US (or every voter, for that matter) would surely admit the thought has at some stage crossed his or her mind. Will the President survive his term? Where and how would it happen? What would happen in the aftermath? How on earth would the world react?
Lincoln, Garfield, McKinley and Kennedy. There's good reason President Obama's victory speech was delivered behind walls of bulletproof glass.
It is most unlike the Catholic Church, of course, to ever be considered at all behind the times. What a relief, therefore, for the Pope to join the norm of most political positions of power, in relinquishing top office before slipping off to the other side. It just tends to make transitions a little tidier.
Eight US Presidents have died while still in office, and Barack Obama at least appears to take practical steps to avoid a premature departure. We're told he exercises regularly and at every speech or photo-op his appearance is pre-empted by scores of Secret Service agents, armed and utterly humourless. Rumours abound Obama even occasionally dresses in specially tailored, bullet-resistant clothing.
But the importance or not of a President lasting his term has been emphasised this week, not just by the Pope's premature passing of power (not to be confused with his premature passing), but by an off-hand comment from the former White House doctor, who served sitting presidents. Dr Connie Mariano was asked to consider the presidential potential of Republican Chris Christie.