President Barack Obama's nominee to become the next U.S. ambassador to Iraq withdrew his name on Monday after Republican lawmakers questioned his suitability following revelations that he had engaged in an extramarital affair with a journalist who later became his wife. Brett McGurk, a long-time Iraq expert who had served on the Bush administration's National Security Council, wrote to U.S. President Barack Obama and Secretary of State Hillary Clinton that he was withdrawing "with a heavy heart." "I believe it is in the best interests of the country, and our life together, to withdraw my nomination and serve in another...