Why is Obama teaming up with Sharpton?

  So what's the motivation behind Obama teaming up with race hustler Al Sharpton?
  Is it desperation?
  Is it payback?
  Is it Obama trying to shore up his whacky left wing base, much of whom have current control of the Democrat party, by identifying with Sharpton, whose reputation as an agitator rivals Jesse Jackson's?
  Did he send out his Education Secretary Arne Duncan to add credibility to his appearance with race hustler and poverty enabler Al Sharpton, whose mug is everywhere on tv when the slightest conflict appears?
  Just who IS Al Sharpton?
  A man with a troubling history, even according to Slate.
  A man with whom we're all familiar, particularly with regard to his habit of leaping to charges of racism without the facts.
  And known for his desire to create controversy and dissension among Americans of all stripes.
  The NYTimes notes, while blandly mentioning that Sharpton as "controversial" nationally (ya think?), that Mr. Obama's approval rating has dropped from 95% to 84% among blacks:

Mr. Obama won 95 percent of the black vote in 2008. Polls have shown his approval among blacks remains high, at 84 percent, while his national approval rating is around 50 percent.

  Gallup also noticed The One's ratings have slipped unexpectedly among Blacks and Hispanics. Unexpectedly. LA Times.
  Byron York at the Washington Examiner notes Sharpton's odd finances, the accusations of theft, the Brawley mess, his association with the Crown Heights riot and the Freddie's Fashion Mart killings.
  But President Barack Hussein Obama says of Sharpton (Washington Examiner):

"The other thing that hasn’t changed," Obama continued, "is the National Action Network’s commitment to fight injustice and inequality here in New York City and across America.  And that's not only a testament to Reverend Sharpton.  It's a testament to all of you who are here tonight.  I want to commend you for the work that you’ve done over the last two decades to lift up not only the African American community but the broader American family. That's what you’re about.

  The broader American family, those who are bullied and intimidated by the threat of being accused of being a racist if you disagree with him? 
  Who says these people are running scared?