Got a couple of answers from Answer.com:
1. Dr. King was a Republican. The Republican Party was formed to help abolish slavery. This seems to be a rather simplistic view, and what some claim.
2. Dr. King was not a Republican. Steve Klein, a senior researcher with the Atlanta-based King Center, said that King never endorsed candidates from either party. "I think it's highly inaccurate to say he was a Republican because there's really no evidence," Klein said. A King biographer, Taylor Branch, also said that King was nonpartisan.
Rev. Joseph Lowery, who co-founded the Southern Christian Leadership Conference with King, said there is no reason why anyone would think King was a Republican. He said King most certainly voted for President Kennedy, and the only time he openly talked about politics was when he criticized Republican Barry Goldwater during the 1964 presidential campaign.
"That was not the Martin I know and I don't think they can substantiate that by any shape, form or fashion. It's purely propaganda and poppycock," Lowery said. "Even if he was, he would have nothing to do with what the Republican Party stands for today."
On hearing of billboards sponsored by the National Black Republican Association and claiming that the Rev. Martin Luther King Jr. was a Republican, Lowery said "These guys never give up, do they? Lord have mercy."http://wiki.answers.com/Q/What_political_party_did_martin_luther_king_jr_supportHovering above Martin Luther King Jr. Avenue in Dallas, a provocative billboard makes a controversial claim in black and red block letters: “Martin Luther King Jr. was a Republican. VOTE REPUBLICAN!”
It's a claim, and a voter registration tactic, that has been used before, despite a decidedly mixed reactions from community members who see it.
The ads posted this year -- as well as similar billboards posted in Austin and in Houston back in 2009 -- are the brainchild of Claver Kamau-Imani, a Houston, Texas, church leader and the founder of RagingElephants.org, a conservative group that aims to recruit more African Americans for the Republican Party.
Kamau-Imani said the use of the American Civil Rights leader and Nobel Peace Prize winner is appropriate and accurate.
“The use of Dr. King, because of him being an icon in the community, we feel would be most effective," Kamau-Imani told CBS DFW. "That’s why we used it. We have the documentation to back the claims we’re making on the billboard.”
This documentation is hard to pin down, however. In 2009, Kamau-Imani told Fox News that King's niece, the Rev. Alveda King, said her uncle was indeed a Republican. But while video of Alveda King's claim is available on YouTube, Kamau-Imani acknowledged there's no documentation to back her up.
That 2009 billboard was taken down early, after the leader of the local New Black Panther Party chapter organized a press conference rallying support against the $3,000 sign.
"Martin Luther King may have very well believed in some of the Christian principles of the Republican Party, but Dr. Martin Luther King was not a Republican or a Democrat," Quanell X told Fox News at the time. "[He] would not be with the party of Newt Gingrich, he would not be with the party of Sarah Palin, he would not be with the party of Rush Limbaugh, Michael Savage or Sean Hannity."
In 2011, Politifact investigated RagingElephant's claims, enlisting the help of several noted historians and King biographers.
Thomas Jackson, a history professor at the University of North Carolina-Greensboro and author of "From Civil Rights to Human Rights: Martin Luther King, Jr., and the Struggle for Economic Justice," told the fact-checking site that while the Republican party of Abraham Lincoln's era defended black rights, this attitude shifted after the 1870s. Jackson said he would call King a "'tax and spend' democratic socialist."
David Garrow, the author of the Pulitzer Prize-winning, "Bearing the Cross: Martin Luther King, Jr. and the Southern Christian Leadership Conference" said "It's simply incorrect to call Dr. King a Republican," adding that the activist did not ascribe to either party, but almost certainly voted for Democrats John F. Kennedy and Lyndon B. Johnson.
Dr. King's son Martin Luther King III, as well as various other friends have all objected to this label.
Ultimately, Politifact said the claim was false.Back in Dallas, Peter Johnson, an activist who worked alongside King in the 1960s, told CBS that the billboards are simply offensive.
“Using his image is one thing, exploiting his legacy is another," Johnson said. "To distort his legacy, it’s sacred to some of us. We know the suffering and sacrifice that was made.”
http://www.huffingtonpost.com/2012/10/29/martin-luther-king-jr-republican-billboard-texas_n_2039332.htmlHis biography on biography.com mentions no political affiliation.
http://www.biography.com/people/martin-luther-king-jr-9365086