More than in most democracies, American foreign policy making has allowed considerable room for the influence of public opinion. Perhaps the clearest examples can be drawn from the Vietnam War. It was the loss of public support for further escalation as shown in opinion polls and in the results of the New Hampshire primary that led President Johnson to announce in March 1968 the end of that policy and his refusal to stand for election for a second term. Interestingly, the available evidence at the time of this announcement showed that the North Vietnamese and their Vietcong allies had been crushed by the military response to their Tet offensive. Thereafter it became an article of faith in Washington that the United States would not be able to engage in prolonged warfare because it would not be supported by public opinion.