Opposition backlash and platform convergence in a spatial voting model with campaign contributions

This paper investigates the effects of campaign contributions on candidate behavior in elections. The particular focus is on how candidates choose the ir platforms when they know that the positions they take will influence the level of campaign contributions that they (and their opponents) receive fr om concerned interest groups. The analysis is carried out in the context of a simple one-dimensional spatial voting model with two candidates and two interest groups. Since the earliest Hotelling-Downs formulations, a central issue in the literature on spatial voting has been the degree to which, un der various sets of assumptions, the candidates' platforms converge in equi librium. This paper extends that literature by examining how the introducti on of interest groups making campaign contributions affects the degree of p latform convergence. The paper shows that when choosing their platforms, ca ndidates face a trade-off between generating increased support from opponen ts and provoking a backlash from the opposition. An example is developed to illustrate a surprising result that can occur because of the backlash effe ct: the introduction of two extremist interest groups may lead the candidat es to moderate their platforms, resulting in a greater degree of platform c onvergence than would be observed in the absence of any campaign contributi ons.