This is what William Buckley thought of Buchanan
http://www.nizkor.org/hweb/people/b/buchanan-pat/buckley-1991.html
http://frontpagemag.com/2012/ben-shapiro/pat-buchanan-anti-semite/
I think President Reagan can be trusted on this one.
As he aged, Buckley wanted acceptance in liberal social circles and he was jealous of Pat Buchanan:
http://newsgroups.derkeiler.com/Archive/Rec/rec.audio.opinion/2008-03/msg00036.html
There is a great discussion of the book here. Read all the comments, too:
Book Review: Suicide of a Superpower
http://www.freerepublic.com/focus/f-news/2800678/posts