Structural modeling of campaign finance decisions in the U.S. House of Representatives

Computational modeling and quantifying the drivers of modern political campaign finance is an emerging area of interest among researchers, policymakers, and the general public alike. In a federal legislative body like the U.S. House of Representatives, campaign finance decisions or “money flows” between party members are legal and common practice among both political parties for allocating resources and influence. Using extensive data from the Federal Election Commission, we model these money flows as complex networks and explain their formation using exogenous factors, previously only discussed qualitatively, such as seniority, non-coordinated SuperPAC expenditures, and House leadership status. Our results show that these factors have significant and persistent effects on both parties. These findings provide an empirical basis for ongoing debates about term limits in Congress and the role of unlimited independent expenditures by SuperPACs.Author summary: Campaign finance in the United States is often studied through donations from individuals, political action committees, and outside groups, but less attention has been paid to how members of Congress financially support one another within the same party. These internal transfers can reveal how parties allocate resources, reward influence, and respond to competitive elections. In this study, we examine campaign contributions exchanged among members of the U.S. House of Representatives from 2009 to 2022. We represent these contributions as directed networks and use statistical network models to test how structural processes and member characteristics relate to contribution patterns. We find clear differences between the two major parties. Democratic contribution networks remain relatively stable and centralized over time, while Republican networks change more substantially, becoming less centralized and more locally clustered. Seniority, leadership status, and SuperPAC activity are also associated with which members are more likely to give or receive support. These findings show that campaign finance within Congress is not random, but reflects broader organizational features of party politics and changing electoral pressures.