Hideo Konishi

This paper proposes a model of two-party representative democracy on a singledimensional political space, in which voters choose their parties in order to influence the parties’ choices of representative. After two candidates are selected as the median of each party’s support group, Nature determines the candidates’ competence levels. Based on the candidates’ political positions and competence levels, voters vote for the preferable candidate without being tied to their party’s choice. We show that (1) there exists a nontrivial equilibrium under natural conditions, and that (2) depending on voter distribution over their political positions, the equilibrium party line and the ex ante probabilities of the two-party candidates winning can be biased. In particular, we show that if a party has a strong subgroup with extreme positions, then the party tends to alienate its moderate subgroup, and its probability of winning the final election is reduced. JEL Classification Numbers: D72, P16