sorry but you are wrong.. the south up until the 80s were almost all Democrat and they were not hard left. I know what I’m talking about I have lived in the south all my life
First of all, you did not specify “The South” in your post and the Democrats as a party nominated a hard Left anti-war (and all the socialist rhetoric that came with that movement) in George McGovern in 1972.
The McGovern folks took over the platform and moved the party hard Left that year. The party never recovered.
In the mid 60s you had McGovern, and a bunch of other progressively Leftist Democrats buying into the anti-War movement. By 1972, they wrestled control of the party away from the more moderates and we’ve had strident Leftist candidates from the Leftist (Democrats) ever since.
This is not a commentary on the Democrats of the South. It’s just a hard cold fact about the overall party.