When Oprah, one of the world's most influential entertainment celebrities, announced that she'd be backing Barack Obama in the democratic presidential primary many thought this would be a huge benefit to the Obama campaign. Some seemed to think this was the boost he needed to catch up to Hilary Clinton in the polls.
However Oprah's endorsement didn't do much if anything to lift Obama out of a distant second in the democratic race.
Why? It now seems clear that Oprah's legendary influence does not extend into the political realm. I'm guessing there are two key factors here: First, viewers already have their political minds made up for the most part. They'll take Oprah's advice for books or lifestyle or personal training or (sometimes) for the virtues of dieting, but they simply won't change their mind about "important" things. Also, I'd guess the Oprah democraphic lines up strongly with support for Hilary Clinton and those viewers like Clinton for much the same reasons they like Oprah.