White House officials refused to explain Thursday why Chief of Staff John Kelly and others allowed Rob Porter to stay in his high-profile job even after his security clearance was held up over allegations of domestic abuse by two ex-wives. "His background investigation was ongoing," White House spokesman Raj Shah said of Porter, the former White House staff secretary. "His (security) clearance was never denied, and he resigned." Shah would not detail when Kelly and others learned of the allegations, only that they discovered their "full nature" - including pictures of a woman's black eye - on Wednesday.