George Wallace was always a democrat except for that one of his several presidential runs when he went 3rd party and then went back to running for governor (and winning) as a democrat.
MLK wasn’t a republican.
I lived in the Jim Crow South and I can assure you MLK was NOT a democrat in 1954 when he started preaching in Montgomery Alabama.
The South was one party and that party was Jim Crow democrat.
OK, maybe MLK wasn’t attached to either party in the early years... that’s possible.