Huey Long was assassinated circa 1935 in the Louisiana State House surrounded by body guards by a lone gun man. Kennedy had multiple Secret Service Agents. President McKinley was at a Fair, in a crowd and was shot by a lone gun man.
The one advantage Mr. Trump does have is those patriotic bikers which do help the USSC and the private security. On many of the buildings, on the roof tops are pro snippers. The LEFT should simply not mess.
If you are willing to trade your own life you can find a way to get to anyone.