I feel like there is a difference between voting for someone and voting against someone.
I don’t like how noted war criminal amd possible lizard person Dick Cheney endorsed Harris, but Cheney has never said, “I like what Harris is going to do”; instead, he tried to frame it as a vote against Trump because…well, it’s Trump.
And of course, right-wingers don’t have any capability for self-reflection, because the proper response to fucking Dick Cheney calling you evil is to look in the mirror and ask yourself some hard questions.
Prior to Trump it was mostly fringe candidates like Storm Thurmund (1948), George Wallace (1968), David Duke (1988, 1992), Pat Buchanan (1992, 1996).
In terms of major candidates, there are some questionable endorsements for candidates like Nixon and Reagan. But you have to go all the way back to Woodrow Wilson to find a president who was openly happy about receiving those endorsements.
Reagan was endorsed by notorious segregationist Strom Thurmond in 1976, who also endorsed Richard Nixon. Not sure about endorsements, but Woodrow Wilson openly supported the KKK.