Valenti served as liaison with the news media during President John F. Kennedy and Vice President Lyndon B. Johnson's November 22, 1963 visit to Dallas, Texas, and Valenti was in the presidential motorcade. Following the assassination of President Kennedy, Valenti was present in the famous photograph of Lyndon Johnson's swearing-in aboard Air Force One, and flew with the new president to Washington. He then became the first "special assistant" to Johnson's White House and lived in the White House for the first two months of Johnson's presidency. In 1964, Johnson gave Valenti the responsibility to handle relations with the Republican Congressional leadership, particularly Gerald Ford and Charles Halleck from the House of Representatives, and the Senate's Everett Dirksen.