Hot take: Ol' Zig Zag Zell would've narrowly lost in 2004 had he ran as a Democrat. Even at that time, overcoming a 17-point presidential loss in GA would've been
very, very difficult (not to mention how many Democrats he alienated during this time). People are underestimating just how many Dixiecrats died and/or completely flipped between 2000-2004 (see
1998 and 2002 statewide elections for some clarity). Of course, had he planned to run in 2004 as a D, he might not have gone off the rails entirely - which could have
possibly been enough to save him, but I doubt it.
Had he switched parties and ran as a Republican, he would have won - assuming he cleared the primary. However and given GA's primary would've occurred before the RNC convention, I'm not sure he could have zigged and zagged enough to clear somebody like Isakson (who even then was a GOP powerhouse; he "only" lost by 8 to Miller in the
1990 gubernatorial election).