The 2024 Elections and the Nationalization of Congressional Vote Choice

The 2024 cycle offers a crucial case for the nationalization of American elections. We argue that presidential-centered evaluations increasingly anchor down-ballot choice, compressing local heterogeneity and diminishing the independent effects of incumbency and candidate quality. Leveraging Cooperative Election Study data across four presidential cycles (2012–2024), we show that presidential vote intention and partisan identity overwhelmingly structured House and Senate outcomes, with straight-ticket voting at modern highs and ticket-splitting at historic lows. The unusual 2024 campaign sequence—an incumbent’s mid-July withdrawal, rapid party re-nomination, and Trump’s return—further centralized national cues, aligning congressional results with the presidential map. We document strong congruence between presidential and Senate outcomes and a declining incumbency advantage in House contests. Individual-level models reveal that the presidential vote has grown substantially more predictive over time while demographic effects have diminished. We conclude by outlining how Trump-era nationalization shapes governing constraints and implications for future cycles.