Is Karl Rove, according to the Washington Post's Chris Cillizza, in his item today on White House fundraising. I've only heard "Svengali" as a term of derision, since it means "one who attempts usually with evil intentions to persuade or force another to do his bidding" (Webster's). Now, Rove as Svengali is the left's caricature, but Cillizza's column is ostensibly reporting only, not opinion.
I've emailed Cillizza asking if he knows what Svengali means. I'll let you know what he says.