Economic reasoning on the political process usually starts with given normally distributed preferences of voters for ideologies from extremely leftist to extremely rightist positions. The problem then is the optimal adaptation strategy of political parties in order to maximise votes or to get a sure majority. In this article, the standard approach is modified in two respects. First, the linear concept of ideology is replaced by the multidimensional concept of voter satisfaction. Voters are not interested in ideology but in goods and services the political sector can offer them. Therefore, secondly, voter satisfaction is made endogenous depending on the political activities of the parties. Combined with some standard assumptions of the economic theory of democracy, there results a dynamic model of voter satisfaction and long-term stability of the parliamentary system. The outlook the model gives for parliamentary democracy in the long run is not very optimistic. Competition compels parties to maximise votes in the short run by activities which dangerously diminish voter satisfaction in the long run.
