When King was imprisoned shortly before the election, Wofford and Shriver persuaded Kennedy to call King's wife, Coretta Scott King, who faced the specter of her husband sentenced to hard labor in a Georgia prison for a minor traffic violation while she was in an advanced stage of pregnancy. This prompted Martin Luther King Sr. to switch his endorsement from Richard Nixon to Kennedy without the knowledge of Ted Sorensen, Ted Kennedy and Kenneth O'Donnell. Following the phone call, Wofford and other Kennedy aides assembled a pamphlet that referenced the call, printed on blue paper and known as the "blue bomb"; some 2 million copies were circulated, mostly through African American churches—"below the registry of the news and white culture. It had enormous influence among black voters."