The words "powerful" and "effective" don't do this short segment by Melissa Harris Perry justice.
"This may be practical political strategy: fear of the 'dangerous black man,' resentment for the mythical 'welfare queen.' It has worked before, but it will not work much longer, 'cause it's not a dog whistle. We can hear you. And we're calling you on it."
Related post here. And back in 2010, Rachel Maddow covered the fears of the GOP feeling threatened by a white minority here: “Be afraid, white people! The black people are coming for you!”