Unlike Donald Trump (whose father apparently was in the Ku Klux Klan), Ronald Reagan (whose father was a Catholic) knew how to criticize the KKK directly:
Letter to the Chairman of the Commission on Civil Rights Concerning the President's Views on the Ku Klux Klan
April 30, 1984
While in China, I have been distressed to learn that some individuals back home have questioned whether my views on the Ku Klux Klan have somehow changed since 1980. Nothing could be further from the truth.
In 1980, I said that I have no tolerance for what the Klan represents, and would have nothing to do with any groups of that type. If anything, my feelings on this subject have only grown stronger. The politics of racial hatred and religious bigotry practiced by the Klan and others have no place in this country, and are destructive of the values for which America has always stood. Those of us in public life can only resent the use of our names by those who seek political recognition for the repugnant doctrines of hate they espouse.
I firmly believe that there is no room for partisanship on this question. Democrats and Republicans alike must be resolute in disassociating ourselves from any group or individual whose political philosophy consists only of racial or religious intolerance, whose arguments are supported only by intimidation or threats of violence.
We must, and will, continue our unified rejection of such elements of hate in our political life, for while there are many issues which divide us, it is fundamental principles such as this which will always draw us together.
[The Honorable Morris B. Abram, U.S.. Commission on Civil Rights, 1121 Vermont Avenue, N.W., Washington, D.C. 20425]