More on Alexander's competition, John W. "Jock" Scott. Seems Scott also switched parties, from Dem to Repub, back in 1985. Before that, Scott (according to an unsubtantiated source) served as Gary Hart's Louisiana campaign coordinator during Hart's first presidential campaign in 1984.
Actually, as far as I can make out, Scott has never been the Republican favorite in the district. According to a local political forum PoliticsLA.com, scuttlebutt had it that one or two other heavyweights, Fletcher and Holloway, were expected to qualify at the last minute. Neither did, which at the very least suggests they might have been given a heads up. In which case we can expect to see the NRCC support Alexander whole hog.
Another interesting tidbit about Louisiana politics: according to a recent editorial in the Baton Rouge Advocate, there have been a number of switches in LA the past few years. This includes Governor Mike Foster (switched in 1995 as he was entering the governor's race) and current Majority Whip Billy Tauzin (switched in 1995 or 96--perhaps not coincidentally right after the House switched to Repub control for the first time in his now 24-year stint--the guy likes to be in power).