Was Martin Luther King Jr a Republican Or Democrat?

I really like to know about the history of my country and this time I was searching about Martin Luther King Jr, and I couldn't find if he is a Republican or a Democrat. I'm not sure, because some people say he was Republican but others affirm he voted for the Democratic party. Martin Luther King Jr, was a great man, he fought for the black's rights, and I'm really proud of him.
Do you know if Martin Luther King Jr was a Republican or a Democrat?

As you said, there are a lot of pages on the internet talking about Martin Luther King Jr as a Republican and others saying he was Democrat, so I think that probably we will never know for sure, but there are some things we know that can help us to understand him a little more.
Martin Luther King Jr said that he was in the position of non-alignment, so you can look objectively at both parties. This is really important, because you must know the strengths and the weaknesses of both of this parties. According to him, he doesn't think that the Republican party is full of the almighty God nor is the Democratic party. People said he was register as a Republican even he always voted for the Democratic ticket, and that's why this is so confusing.
Martin Luther King Jr was a great man, and sometimes it doesn't matter if he was a Republican or a Democrat, because after all the things he did, this is no important.