Deep-seated racial misgivings could cost Barack Obama the White House if the election is close, according to an AP-Yahoo News poll that found one-third of white Democrats harbor negative views toward blacks — many calling them "lazy," ''violent" or responsible for their own troubles. The poll, conducted with Stanford University, suggests that the percentage of voters who may turn away from Obama because of his race could easily be larger than the final difference between the candidates in 2004 — about two and one-half percentage points.