This study shows that intra-party competition shapes campaign messages well before candidates enter office. Analyzing 1,394 campaign brochures from South Korea’s multi-member districts, I develop a supervised text measure of particularistic appeals and test how they vary with co-partisan rivalry. Candidates facing more same-party competitors consistently emphasize narrower, targeted benefits. The commonly used C:E measure, however, performs poorly because nominations respond more to short-term electoral sentiment than to expected seat counts. These findings demonstrate how measurement choices reshape inferences about personal-vote strategies and highlight the value of integrating text analysis with qualitative evidence. 

Candidate-centered electoral rules can fuel corruption not only during campaigns but throughout legislators’ terms. Focusing on South Korea’s SNTV local councils, I show that co-partisan incumbents who share a district face persistent intra-party rivalry—an institutional pressure that drives personalistic and corrupt behavior. Using a ten-year panel of council-level corruption outcomes and a causal forest design, I find that corruption rises substantially as the share of these co-partisan incumbents increases, especially where inter-party competition is still meaningful. The study reframes corruption under candidate-centered systems as a product of post-election incentives, offering a new account of how electoral rules shape legislative conduct.