Ban Ki-moon, the South Korean foreign minister, moved significantly closer on Thursday to becoming the successor to Kofi Annan as United Nations secretary general by maintaining a wide lead over six other candidates in the Security Council’s third informal poll. A fourth and more definitive informal poll is scheduled for Monday, and Ban, with 13 favorable votes from the 15 Council members, goes into that poll as the only candidate with the 9 votes required for approval. Full Story