An election too far: Why do MPs leave politics before an election?

Why are members of parliament retiring? In most parliamentary systems, a substantial number of MPs decide, before every election, not to run again. Though the decision to leave politics is essentially personal, a broader look at a large sample of MPs can reveal the existence of structural factors such as an uneven playing field or other sources of discrimination that could explain why certain individuals stay while others leave. A survey of the current literature indicates that the empirical work on this topic is almost exclusively focused on the US Congress. There is thus a need to conduct more research in other contexts to generate a more general explanation of why MPs leave politics on their own terms. The current literature suggests that the decision to leave could be explained by a complex combination of variables that are personal, partisan, and contextual. The purpose of this article is to better understand why sitting MPs decide not to run for re-election in parliamentary systems, focusing on three Westminster systems: Australia, Canada, and New Zealand since 1945. Various factors play a role, but our results suggest that as time passes, parliamentarians simply become less prone to seeking reelection.