Pre-1964 or so I could see why Martin King was a Republican. Lets face it, the GOP was home to an overwhelming amount of African-Americans. Because of the Civil War, the freeing of the African slaves, Abraham Lincoln, etc. And then go up to the 1950s and 60s, which party is the civil rights party? The Republican Party and their Northern Progressives, especially in Congress. Who without the 1964 Civil Rights Act, the 1965 Voting Rights Act and the 1968 Fair Housing Law doesn’t pass. Those laws would’ve not of passed in the House and Senate without Northern and Midwestern Progressive and Conservative Republicans. Like Senate Minority Leader Everett Dirksen.
Ideologically except for civil rights, its hard to imagine how MLK would’ve fit into the Republican Party. They did have a progressive faction, but that was about civil rights, infrastructure, environmental protection and to a certain extent the safety net for people who truly needed it. But MLK was much more social democratic in nature, especially economically and when it came to civil rights and racial equality in general. And he was a dove and non-interventionist when it came to foreign policy and national security. And consistently spoke out against the size of the American defense budget and our involvement oversees. But without putting down American serviceman and women. Unlike the New Left of the late 1960s.
I can’t imagine Dr. King as a Republican or Democrat back then and perhaps not today. Today I could see him putting down Democrats as giving up on the poor and less-fortunate over things like Welfare to Work. And not doing enough to address the income gap and eliminate what he and others see as the Military Industrial Complex and Prison Industrial Complex. If Dr. King were a Democrat today, he would’ve been a member of the Progressive Caucus and perhaps one of the leaders of Occupy Wall Street, or creating his own social democratic movement. Or perhaps not a Democrat at all and a member of the Green Party or Democratic Socialists USA. He was very Left on economic policy and when it came to national security as well, for a lot of center-left Democrats.