When I was in college I read a whole lot on Malcolm X. Much of it was about his complex relationship with, perhaps more accurately, to Martin Luther King, Jr (to my knowledge they met only once). I more than once came across a particular historical account in which Martin Luther King's successes were nonetheless seen to owe a significant debt to Malcolm. The point these writers made is that Malcolm X was so damn crazy he made MLK look, by comparison, much more acceptable in the eyes of established elites and skeptical publics.
I can't verify if it's a valid historical account, but I think of the notion lately when I read the economist Paul Krugman and his criticisms of President Obama. If MLK had Malcolm X, Obama seems to have Krugman, whose existence in the pages of the New York Times forcefully arguing for more, more, more demand-side redistributions of wealth -- not to mention his loud advocacy of temporary nationalizing four or five of the country's largest banks -- gives Obama a very public guy about whom the president can say to his conservative critics: If you think what I am demanding is unreasonable, you should recognize that Krugman's the alternative. Be glad you got me because I ain't like that.