Discuss the role of policy maker
A policy maker, who focuses mainly on the possibility of remaining in the office, faces different set of incentives in choosing policy. He tries to choose policies in order to influence the policies of his successor, either by making such policy choices which increase the probability of winning the election of those who have similar policy preferences, in other words, from his own party, or by influencing rival's policy choices. The question is, how can a policy maker affect the choice behaviour of his rival with respect to policy preferences? He does it by altering the constraints his rival will face if he wins the election.
For example, he may choose such a policy, which will affect the rival when outcome of his policy will appear by the time his rival will hold the office. Or, another common example may be change in the boundaries of the electoral constituencies, and thereby changing the voter compositions itself. The model developed by Ferejohn (1986), presents the effects of elections on the behaviour of the incumbent as well as voters. With assumption of homogeneous voters, he sets the problem under principal-agent framework. However, when electorates are heterogeneous, the ex-post heterogeneity comes to play. In that case an incumbent may become able to play voters against one another.