Via Marc Ambinder, Carnegie Mellon's student newspaper, The Tartan, exposes the sausage-making that goes into an Obama campaign event:
While the crowd was indeed diverse, some students at the event questioned the practices of Mrs. Obama’s event coordinators, who handpicked the crowd sitting behind Mrs. Obama. The Tartan’s correspondents observed one event coordinator say to another, “Get me more white people, we need more white people.” To an Asian girl sitting in the back row, one coordinator said, “We’re moving you, sorry. It’s going to look so pretty, though.”
“I didn’t know they would say, ‘We need a white person here,’?” said attendee and senior psychology major Shayna Watson, who sat in the crowd behind Mrs. Obama. “I understood they would want a show of diversity, but to pick up people and to reseat them, I didn’t know it would be so outright.”
Ambinder deems this "[a] rare, unforced error committed by the Obama campaign's site advance teams"; but I don't really see how. Clearly, the Benneton-ish displays of diversity on the risers behind Obama (and Hillary, too) don't just happen by accident; the campaign advance teams are exquisitely sensitive to the racial make-up of the people standing behind the candidates, so, inevitably, they shuffle people around to make a prettier picture. I guess the error is the actual use of the words "white person" when doing the shuffling. Maybe they need to develop some code words: "We need a scoop of vanilla in the second row!"
--Jason Zengerle