In the end, the KKK did not choose to support Donald Trump because he was a Republican but because they agreed with the ideas that he (and other far-right Republicans) spout. It is finally time to face the rise in the twenty-first century of a new form of white nationalism and its alignment with many leaders of the Republican Party, including Trump.
And Johnson did it begrudgingly because he was a racist piece of shit. Carter was the first Democratic president who actually cared.