CREDIBILITY GAP. Term used to criticize a public figure or institution by suggesting that there exists a "gap" between official claims and the public's perceptions. In short, the term alleges that the people do not believe what they are being told.
The phrase first appeared in 1965 newspaper stories concerning the policies of President Lyndon Johnson. Several accounts claimed that Johnson had frequently been duplicitous in announcing one policy and then enacting another. The most politically damaging example involved the 1968 Tet Offensive in Vietnam, which caught the U.S. military completely by surprise after Johnson had spent months predicting imminent victory.
Gardner, Lloyd C. Pay Any Price: Lyndon Johnson and the Wars for Vietnam. Chicago: I. R. Dee, 1995.
Turner, Kathleen J. Lyndon Johnson's Dual War: Vietnam and the Press. Chicago: University of Chicago Press, 1985.