Determinants of the Outcomes of Midterm Congressional Elections

TLDR

Midterms serve as a referendum on the President’s performance and the administration’s economic management. The study develops an explanatory model for the outcomes of midterm congressional elections. The model incorporates vote‑to‑seat translation, electorate and individual voter models, and factors driving the President’s party’s off‑year losses. It delivers accurate pre‑election predictions of national two‑party vote shares, consistently outperforming survey‑based forecasts.

Abstract

An explanatory model for the outcomes of midterm congressional elections is developed. Midterms are a referendum on the performance of the President and his administration's management of the economy. The explanatory model of midterm congressional elections is sufficiently powerful so as to yield honest and accurate pre-election predictions of the national two-party vote in midterm elections. These predictions have usually outperformed pre-election forecasts based on survey data. The model is extended by considering the translation of votes into seats, models of the electorate as a whole and of the individual voter, and the causes of the off-year loss by the President's party.