Senator Obama, an Illinois Democrat now seeking the presidency, suggests in his book that his years in New York were a pivotal period: He ran three miles a day, buckled down to work and “stopped getting high,” which he says he had started doing in high school. Yet he declined repeated requests to talk about his New York years, release his Columbia transcript or identify even a single fellow student, co-worker, roommate or friend from those years. “He doesn’t remember the names of a lot of people in his life,” said Ben LaBolt, a campaign spokesman. Mr. Obama has, of...