Trying to be serious (I'm always trying), how many times did crazed right-wing Fundie gun-nuts try to shoot Obama? How many times did crazed right-wing Fundie gun-nuts try to shoot Clinton? Carter? LBJ? The last two Presidents to have been shot or who were the target of an attempted shooting were Reagan (John Hinckley) and Ford ("Squeaky" Fromme, who didn't chamber a round in her .45). Hinckley was a fruitcake, and Squeaky was a left-leaning fruitcake.
If either candidate should be particularly worried about assassination attempts from people of particular political leanings, it's R and conservative candidates who should be particularly concerned, and about extreme and/or fruitcakey left-wing people.