ABSTRACT: Research in many countries shows that where voters and campaign workers are motivated by material rewards, the brokerage networks delivering those rewards can be highly unstable. Brokers often exercise considerable autonomy, shifting between candidates, disobeying their directives, or stealing the cash or goods they are supposed to pass on to voters. What determines whether brokers betray their ca ndidates in such ways? This article answers this question by focusing on elections in Indonesia, where candidates construct ad-hoc "success teams" to organize brokers and mobilize voters. In proposing a model to explain broker behavior, the author proposes the division of team members into three categories: activist brokers, who support a candidate based on a political, ethnic, religious, or other commitment; clientelist brokers, who desire long-term relations with the candidate or with more senior brokers, with the goal of receiving future rewards; and opportunist brokers, who seek short-term material gains during the course of a campaign. Two problems of broker loyalty are then discussed, specifically: predation, where brokers misappropriate resources intended for voters or lower-level team members, and defection, where they desert one candidate in favor of another. Explaining the incidence of these phenomena, the author examines two key factors: the material endowments of candidates and broker evaluations of their prospects of electoral victory. Well-resourced candidates with poor prospects are most likely to experience predation, whereas less materially endowed candidates will experience defection. The article concludes by addressing the implications for studies of clientelism and brokerage.