This is the inconvenient truth that leftists would prefer to deny, and one of the reasons why there's so much shrieking about Trump and Bannon and Brietbart.
They've mastered using the left's tactics against them.
Left, what left? What is going on in DC right now is a fight between two segments of the right wing. There has been no Left in USA sine the 70s at least.
Donald Trump exhibits every defining factor of being a fascist. He's authoritarian and very pro-military, he's nationalistic, he paints other religions and ethnicities as being evil, he paints other nationalities as being evil, he is protectionist, he's anti-media, he's anti-independent judiciary...
> paints other religions and ethnicities as being evil
> paints other nationalities as being evil
> anti-media
> anti-independent judiciary
None of those views fall very far outside of mainstream Republican belief. Trump just replaced the typical dog-whistle with a bullhorn, because he's politically incompetent, and was far more blatant in pandering openly to the fringe.
The difference is he has a personality disorder, extreme narcissism, that verges into sociopathy. If such an individual gets hold of a position of power, they can ruthlessly "split" the people around them, and exert greater than proportional influence. Whether this meets a technical description of fascism or not, it puts him in a category with authoritarian despots, who rule with no regard for the welfare of anyone besides themselves.
None of those things (except pro-military, but every party in the US is pro-military, that's what you get when you're the only empire on earth) are typical of the republicans. The republicans, despite what you might (incorrectly) think, are not represented well by Trump.
They've mastered using the left's tactics against them.