Katie Zacharia, the new White House press secretary, announced during her first briefing that the administration had asked Guilfoyle to resign. Kimberly Guilfoyle, the U.S. ambassador to Greece, resigned on Tuesday amid allegations of improper conduct while denying the claims and vowing to "vigorously defend" herself that Guilfoyle asked a Trump donor to pay off a $100,000 American Express credit card bill ahead of her confirmation as ambassador in exchange for access to administration officials.