The stability of voting behaviour was a central finding of the pioneering studies of the 1950s and 1960s (Berelson et al. 1954; Campbell et al. 1960; Lazarsfeld et al. 1968 ). According to the classics, voting was to be explained on the basis of long-term factors, such as one's position in the social structure, or traditional loyalties acquired through socialization. In line with this, the electorate was said to be largely immune from the short-term influence of campaign activities, which could only contribute to a reinforcement ofpredetermined intentions.