They were both Dems. The article about MLK being a Republican was debunked a long time ago. He was very enamored of big government, Socialist solutions to problems.
The Republican Establishment propaganda regarding the King Family is too thick for me to eat, much less swallow.
Dr. King’s father was supportive of the GOP for many years but MLK and his dad (1960) did support JFK in the end, then MLK went to work with protests to force the Democrats to back away from the segregationists in their ranks.
This led to MLK supporting LBJ in 1964 but he broke ranks with the Dems over the Vietnam War joining the anti-war protest movement.