The multiple patterns of factional influence: Evidence from the 2021 LDP presidential election

Traditionally, factions and seniority determined who became President of the Liberal Democratic Party (LDP) and, thus, Japan's Prime Minister. Since the electoral reform of 1994, however, some scholars have argued that the role of factions has declined, and this has led to ongoing debates over the extent to which factions and other factors have helped determine who will become the leader of Japan's LDP. Using data from the 2021 LDP Presidential election, we find that it is not policy but factional affiliations that matter for LDP members in selecting their leader. In addition to this finding, we disaggregate faction and show that the influence of this political institution in LDP Presidential elections varies across different factions. We also find that electorally weaker LDP incumbents are more likely to support a candidate who is more popular among Japanese voters in general.