It's true, the KKK was once primarily comprised of southern Democrats.
That has changed.
Former Grand Wizard David Duke (his ex-wife co-founded stormfront.org - the Internet's first major hate site) was a Louisiana House Representative from 1989 to 1993. He was a Democrat until 1988 (he couldn't win as a Democrat), but subsequently switched his party affiliation to the Republican Party and won his LA house seat.
http://www.stormfront.org (the Internet's first major hate site)
It's funny - most of the comments at stormfront.org sound like comments that could have been made at townhall.com - except they are generally much more polite and coherently-written.