Ideological versus Downsian political competition

We analyze a one-dimensional model of spatial political competition with two parties and uncertainty on the distribution of voters types. We assume that parties are formed by regular members and professional politicians; members care about the policy enacted, while professional politicians, on the contrary, only care about winning the election. We consider two possibilities: that member choose such platforms. The expected utility for party members is analyzed under these two cases. We find that when professional politicians have no informational advantage, it is on the interest of both parties to let professional politicians choose the platforms. Only in the case in which professional politicians have better information than the members of the party about voters is it possible that party members obtain a greater expected utility choosing the platforms themselves rather than letting the professional politicians choose