Reagan called the ANC “notorious terrorists,” and, as late as 1988, called apartheid "a tribal policy more than ... a racial policy."Of course, these attacks are only in the past because Mandela retired from public life -- and some of the wingnuts are no longer alive.
It wasn’t just Reagan. Moral Majority leader Jerry Fallwell called [Desmond] Tutu a “phony” who didn’t speak for South Africans blacks. He even urged Americans to support the Pretoria government. North Carolina Senator Jesse Helms filibustered the sanctions bill. Strom Thurmond and Phil Gramm likewise opposed it. And future vice-president Dick Cheney called Mandela a terrorist, saying in 2000 that he didn’t regret his position. Pat Buchanan called Mandela a “train-bomber.” The Heritage Foundation said America should stop calling for Mandela’s release from prison. Pat Robertson, Grover Norquist, future Tea Party leaders, and current Republican Senators—all were on the books supporting the Apartheid government. When 35 House Republicans broke with the Reagan administration, the National Review called them “uppity,” and Human Events called them a “lynch mob.”
Here's a bonus wingnut hack attacking Mandela more recently.