I've talked to the FBI before about threatening posts that certain websites won't delete. They reminded me that most such posters are just full of hot air, and it has to cross the line into overt intention versus 'somebody oughta'. But the most rabidly serious threats against the life of the President, I have reported a few of those in the past. And will continue to do so.
The tiny midwestern town where I retired a few years ago is a teabagger/paramilitary hotbed, and at first I got threats myself because I'm crazy enough to march around town wearing Democrat-themed outfits. I write letters to the editor of the local weekly Repug ragsheet. But the closest someone's come to actual violence is to throw the occasional beer bottle at me from their passing pickup when they see me on foot or riding my bicycle.
For the first few years there was a concerted effort to run me out of town on a rail. The knuckle draggers wanted me off the weekly mini-bus run so much that they finally turned in a false police report that I carried a gun on board and threatened everybody. (I never did - mostly I just laughed at them when they screamed in my face.) Fortunately the police chief has enough brain cells to know who was lying, but the law still wouldn't do anything to them either for their many misdemeanors and even felonies.
There's something Orwellian about drug-addled trogs (2 are certified mental cases) preaching to me about freedom, religion, and ethics. Of course I've been denied most avenues of social life, but I don't care for the society of those types anyway. A few good people have sent me complimentary letters, but in this town where everyone knows everyone else's business, nobody had nerve to sign their encouraging messages! Too scared of the rough crowd.
Anyway, most people don't harrass me openly too much anymore, because when they do I have ways of making them think twice about a second try at me. They know I don't run though I do fight back, even if it's only holding them up to public view in the paper.
But I don't worry about the President's safety too much, not like at first. He's very heavily guarded, and nobody's fool. As for the internet trolls, I do prefer they crap in their own living rooms, not those intended for civilized folk.