Although many system dynamists point out the close relationship between institutional economics and system dynamics, the relationship between institutional political theory and system dynamics approach is not explicitly appreciated yet. We developed a system dynamics model to investigate theoretical propositions of institutional politics. Our system dynamics model showed how the endogenous mechanism can explain the political changes as well as orders. Although simple in the causal structure, our model could show a complex behavior of political competition. Several simulation results imply that some unexpected changes in election and power competition may come from the endogenous system rather than from exogenous factors such as economic and environmental shocks.