In a roughly bipolar political system, the national election outcomes often depend on the behavior of a minority of "marginal" voters who make their decisions at the very moment of voting and/or choose a candidate who belongs to the opposite political camp with respect to their previous choice. These segments of the electoral market are the natural target of political strategists and campaigners, whose goal is to reach and persuade a majority of potential voters using an essentially media-based communications strategy. This article inquires into the attitudes of marginal voters towards politics, their ideological beliefs, as well as their basic sociological features. After drawing the portrait of a citizen who seems mostly apathetic towards the political process, the author discusses the implications of this empirical evidence in relation to the individual logic of voting. In order to explain the electoral choice of marginal voters, the author sketches the theoretical outlines of a new "impressionist" hypothesis as a viable alternative to the traditional explanatory models of electoral behavior based either on "determinist" or on "rationalist" assumptions. The empirical analysis focused on 1996 Italian and 1997 French national elections.