We all know that President Long so nearly was not. Although he had announced his intention to run in 1935, the bullet that kept him in hospital for three months in 1935 came within millimetres of ending his life. It seems certain that Roosevelt and his fellow travelling vice president, Henry Wallace would have remained in power if that had happened. No doubt, Roosevelt would have found some pretext to enter the War in Europe rather than simply bankrolling the British War Machine and lending scientific expertise to the Montreal Project which led to the British development of the Atomic Bomb. (Obviously, as Secretary of the Navy, Roosevelt was in any case heavily involved in the Montreal Project, but imagine if he had been President... would the Montreal Project be the Manhattan Project?)
Of course, much more important would be Huey Long's domestic policies. Roosevelt supported many of Long's reforms once Long had replaced him as Democratic Candidate and as President but would he have been very different. Would he, for example have been able to use, as Huey Pierce Long did, the threat of an imminent war to force the Bankers to accept his banking reforms. Would he have tried, as Long did, to redistribute wealth from Rich to Poor and if he did, would he have succeeded or would he too have found America spiralling into a second Depression, only to be saved by the Japanese attack on Pearl Harbour.
And what of his response to Pearl Harbour. Would Roosevelt, like Long have fought a war against Japan whilst Britain and the Soviet Union fought a separate war against Nazi Germany? A war that Britain was able to win only through the use of Atomic Weapons on Munich and Frankfurt. Or would Roosevelt have embroiled us in the European War and thus delayed our inevitable victory agaisnt the Emperor's forces? Of course, Franklin Roosevelt was supportive of President Long's policies, but that is not the same as saying he would have done the same thing.
I believe we can be sure that in surviving the bullet in September 1935, Huey Long changed the course of History.