Supersedes Working Paper 19-07- Incumbency Disadvantage of Political Parties: The Role of Policy Inertia and Prospective Voting, Supersedes Working Paper 17-43 - Incumbency Disadvantage in U.S. National Politics: The Role of Policy Inertia and Prospective Voting, Supersedes Working Paper 16-36 -Incumbency Disadvantage in U.S. National Politics.

We show that this fact can be explained by a combination of policy inertia and unpredictability in election outcomes. A quantitative analysis shows that the observed magnitude of incumbency disadvantage can arise in several different models of policy inertia. Normative and positive implications of policy inertia leading to incumbency disadvantage are explored.