I read Primary Colors when it came out in paperback. It’s amazing that Klein could defend Clinton back then after portraying him as a horny Arkansas boob in the novel. One would think the novel portrayal was how Klein really saw him. The ‘rats sure know how to circle the wagons.
You will recall another character in Primary Colors with a serious drug history. It's been many years since I read the book, but iirc, the character is somewhat extraneous and the drug stuff is forced. I've always suspected Klein was using the character to signal on Clinton's drug use -- i.e., there were actually two Clinton surrogates in the book.