Who Controls the Agenda Controls the Polity

This paper models legislative decision-making with an agenda setter who can propose policies sequentially, tailoring each proposal to the status quo that prevails after prior votes. Voters are sophisticated and the agenda setter cannot commit to her future proposals. Nevertheless, the agenda setter obtains her favorite outcome in every equilibrium regardless of the initial default policy. Central to our results is a new condition on preferences, manipulability, that holds in rich policy spaces, including spatial settings and distribution problems. Our results overturn the conventional wisdom that voter sophistication alone constrains an agenda setter’s power. JEL Codes: D72, C78

💡 Research Summary

The paper develops a dynamic model of legislative decision‑making in which a single agenda‑setter can propose policies in real time, adapting each proposal to the current status‑quo that results from earlier votes. Voters are fully sophisticated and cannot commit to future actions, and the agenda‑setter also lacks commitment power. The authors introduce a novel preference condition called “manipulability”: a collective‑choice problem is manipulable if, for every policy that is not the agenda‑setter’s top choice, there exists another policy that both the agenda‑setter and a majority of voters strictly prefer to the former. This condition is shown to hold in rich policy environments, including spatial models with three or more dimensions and a broad class of distribution problems; adding transfers or pork to any collective‑choice problem makes it manipulable under virtually any voting rule.

The core result is an “if and only if” theorem: provided the number of voting rounds is sufficiently large, the agenda‑setter obtains her most‑preferred policy in every subgame‑perfect equilibrium, regardless of the initial default, if and only if the underlying collective‑choice problem is manipulable. The proof rests on a simple one‑step improvement argument: whenever the current default is not the agenda‑setter’s favorite, she can propose a policy that a majority prefers to the default, and manipulability guarantees such an improvement exists. Repeating this improvement for T rounds yields a policy arbitrarily close to the agenda‑setter’s ideal; with enough rounds the ideal is effectively achieved.

The authors quantify “sufficiently many rounds”: under simple majority rule three rounds suffice, while for veto‑proof rules the required number never exceeds the number of voters. They compare the real‑time agenda‑control model to a benchmark where the agenda‑setter can commit to a fixed sequence of proposals. In the commitment benchmark the agenda‑setter is limited to the set of policies reachable through a finite chain of majority improvements (as characterized by Miller 1977). By contrast, without commitment the agenda‑setter can achieve her favorite outcome directly, demonstrating that commitment is not necessary for dictatorial power when manipulability holds.

A protocol‑equivalence theorem shows that the same equilibrium outcome arises across a variety of legislative procedures—closed‑rule, successive‑procedure, open‑rule bargaining—so long as the manipulability condition is satisfied. The paper also highlights the strategic role of deadlines: a fixed termination point enables the agenda‑setter to secure her favorite outcome, and she prefers a moderate number of rounds to either a single round or an indefinite process.

Policy implications are stark. Voter sophistication alone does not curb agenda‑setter dominance; bundling policy choices with transfers or pork actually expands the agenda‑setter’s power, making many voting rules effectively dictatorial. The findings call for institutional designs that limit real‑time agenda control or restrict the use of transfers in collective‑choice settings to preserve democratic balance. Overall, the study provides a unifying condition—manipulability—that determines when an agenda‑setter can wield dictatorial influence across diverse policy spaces and legislative institutions, even in the absence of commitment power.