Why Caucuses? Factions as Secondary Heuristics

Why do politicians join factional caucuses? This paper argues that members of Congress use ideological membership organizations to construct and cultivate faction brands. Using data from the 107th to the 112th Congress, I test conditions that are consistent with a theory of caucuses as auxiliary instruments, used to improve the probability of legislative and electoral victory. I find that politicians are most likely to use caucuses when faced with (1) conditions of electoral vulnerability and (2) congressional districts that look very different from the median member of their political party. These results lend plausibility to a theory of factional caucuses as secondary heuristics.