Even when King was alive, his opponents distorted his words, Branch says. They would publicly agree with some of his message while undercutting the parts they didn't like.
"Most people who were uncomfortable with his message did not take it head-on and say Dr. King was wrong because his message was so powerful, and near the heart of patriotism. They would say, 'I agree with you except you shouldn't break the law,' or 'you shouldn't mix church and state' or 'stop corrupting the lives of youth,' " says Branch, who just released "The King Years," a book that looks at 18 pivotal events in the civil rights movement.
One of the first leaders to invoke King's message in support of conservative ideas was Ronald Reagan, according to Stephen Prothero, who spotlights that moment in his book "The American Bible," which examines the most famous speeches and texts in American history.
In June of 1985, Reagan cited King's "content of our character" line from the "I Have a Dream" speech to argue in a speech opposing affirmative action that King's vision of a colorblind society would not include racial hiring quotas.
Reagan, who opposed the Civil Rights Act of 1964, said in a radio address on civil rights:
"The truth is quotas deny jobs to many who would have gotten them otherwise, but who weren't born a specified race or sex. That's discrimination pure and simple and is exactly what the civil rights laws were designed to stop."
Prothero says King's "I Have a Dream" speech has since been invoked by conservative leaders such as William Bennett and Rush Limbaugh to argue that affirmative action equals reverse discrimination.
King a defender of traditional values?
The arguments for King's conservative legacy, however, have acquired deeper layers over the years.
In a 2006 essay entitled "Martin Luther King's Conservative Legacy," Carolyn. G. Raney argues that King's message was "fundamentally conservative" on other levels.