Nancy Mace has fired back at Democratic Congresswoman Alexandria Ocasio-Cortez, saying she lives "rent-free" in the New York representative's head, after she accused the South Carolina congresswoman of "endangering women" with her transgender bathroom ban measure.A row has erupted on Capitol Hill over a bill proposed by Mace seeking to ban House members and staffers from "using single-sex facilities other than those corresponding to their biological sex."The measure covers bathrooms in the Capitol and House offices, charging the House sergeant-at-arms with enforcing the prohibition. It comes after the United States elected its first every transgender member of Congress, Sarah McBride, who will represent Delaware's at-large congressional district in the U.S.