Barack Obama needs to be consistently polling above 50 per cent in crucial states to win, a former Republican convention manager writes in Slate.

“If history is any guide, Barack Obama, as an African-American candidate for political office, needs to be polling consistently above 50 percent to win. And in crucial battleground states, he isn’t.

“Much has been written about the so-called Bradley Effect, in which voters lie to pollsters about whether they’re willing to vote for a black candidate. The Bradley Effect is meant to explain why, for example, Doug Wilder had a healthy 9-point lead up to Election Day in the 1989 Virginia governor’s race, and a similar lead in exit polling, only to squeak through to victory by one-half of 1 percent.”

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