President Trump has said nothing in support of white supremacists, and has specifically condemned them in the harshest terms several times over the past week.
An awful lot of people think the opposite is true. They think Trump has excused white supremacists and can't bring himself to condemn them.
Now, why do people think this when the opposite is true? They think this because the media keeps telling them this. Repeat a lie often enough and people will believe it's true. Who said that? Hitler, right? Yep. Trump is supposed to be a Nazi sympathizer, but the people learning from and practicing Hitler's techniques reside in the newsrooms at CNN, the New York Times and the Washington Post.