Trump seems to have discovered this phenomena that if you repeat a story enough times (even if it's all BS) at least some people will eventually believe it. And that can get you elected in the under the US system.
That was a Nazi technique - the "Big Lie". LBJ also used it, in a nomination election in Texas against Coke Stevenson he accused his opponent of being a socialist, which was not true, and just kept repeating it.