Polling and parliamentary representation: Strategic voting in the 2025 German federal election

How decisive are public opinion polls in influencing the electoral fate of political parties? This article examines this question by focusing on parties at the brink of parliamentary representation. Specifically, Germany's 2025 federal election saw The Left, the FDP, and the BSW hovering around the critical 5% threshold in the polls, with only The Left ultimately succeeding in entering parliament. Drawing on theories of instrumental rationality and information processing, we theorize that polling signals are associated with asymmetric voter responses, with voters disproportionately abandoning parties below the threshold and supporting those above it. Using temporally fine-grained daily survey data together with daily polling scores, we test these expectations. We find that voters have been sensitive to marginal changes in The Left's and the BSW's polling scores, though not the FDP's. Polling at the 5% threshold presented a critical watershed for both parties in attracting strategic voters. This analysis illuminates the relationship between polls and voter decision-making, contributing to broader debates on media influence, voter heuristics, and electoral fairness.