The coalescence of the "alt-right" is the logical culmination of almost 50 years of implicitly racist voter appeals by the GOP.  You want to do away with the "alt-right"?  Stop the GOP from dog whistling. 

Good luck with that.   Without its tacit appeal to disaffected post-1964 whites the GOP couldn't exist.

The modern GOP started with Nixon's "Southern Strategy" in 1968 and took its current form with Ronald Reagan speaking about "states' rights" and "welfare queens" at the Neshoba County fair (in Mississippi) in 1980. The TEA Party took up the torch when the first black president was inaugurated and the current POTUS established his racist political bonafides by, first, calling for the lynching of the Central Park Five and then by being the mainstay of the racist birther movement.