No, MLK Jr. Was Not A Republican.

Click here for an article at Think Progress, "No, Martin Luther King Jr. Was Not A Republican — But Here’s What He Had To Say About Them."

The southern Democrats -- "Dixiecrats" -- were solidly racist and segregationist until Lyndon Johnson shepherded passage of the Civil Rights Act of 1964 and the Voting Rights Act of 1965. At that time, they deserted the Democratic party en masse and moved to the Republican party, where they were welcomed by Richard Nixon with his "Southern Strategy."

Some key quotes from the article:

The Republican Party geared its appeal and program to racism, reaction, and extremism. All people of goodwill viewed with alarm and concern the frenzied wedding at the Cow Palace of the KKK with the radical right. [On the 1964 Republican National Convention.]

[Arizona Senator Barry Goldwater's] candidacy and philosophy would serve as an umbrella under which extremists of all stripes would stand. In the light of these facts and because of my love for America, I had no alternative but to urge every Negro and white person of goodwill to vote against Mr. Goldwater and to withdraw support from any Republican candidate that did not publicly disassociate himself from Senator Goldwater and his philosophy.

The article says:

King barnstormed the country on behalf on Johnson in 1964, “maintaining only a thin veneer of nonpartisanship,” according to biographer Nick Kotz. King called Johnson’s win a “great victory for the forces of progress and a defeat for the forces of retrogress.”

And here is MLK Jr.'s opinion of Ronald Reagan:

When a Hollywood performer, lacking distinction even as an actor, can become a leading war hawk candidate for the Presidency, only the irrationalities induced by a war psychosis can explain such a melancholy turn of events.