Endogenous expropriation and political competition

We develop a game-theoretical model in which the politicians can be influenced by means of campaign contributions of special interest groups. If there is no legally binding contract, politicians have a proclivity to divert some contributions for private use. In doing so, they maximize their own utility which depends on expected election-winning premium and amount of funds misappropriated. We study the utility maximizing fraction of expropriation emerging from the equilibrium policy platform and the associated contribution level. We then compare results under alternative scenarios, namely, one single lobby group versus multiple lobby groups and one-sided lobbying versus two-sided lobbying.