Zalmay Khalilzad, the U.S. ambassador to Iraq, is expected to be nominated the next U.S. ambassador to the United Nations as President Bush attempts to chart a new course for his Iraq policy, two U.S. officials said on Thursday. One official, who spoke on condition of anonymity, told Reuters he understood that the appointment was about to be announced by the White House. A second official said Bush was leaning toward naming Khalilzad and expected him to be nominated. Khalilzad, who had also served as ambassador to Afghanistan during Bush s first term, would replace John Bolton, who left the U.N. post last week.