I am a PhD candidate with the DYNAMICS Research Training Group and a Teaching and Research Fellow at the Chair of Comparative Political Behavior at the Department of Social Sciences, Humboldt University of Berlin. From March to June 2026, I was a visiting researcher at the European University Institute, hosted by Sascha Riaz and Elias Dinas.

I study what (de)mobilizes voters for progressive and Green parties, with a particular focus on gender, age, and economic status. I also work on climate politics more broadly, and have a side project in historical political economy on historical Nazism in occupied Europe. My main methodological interests are quantitative research, causal inference and (field) experimental methods.

If you want to talk about my research, hit me up on Bluesky or via mail.

You can find my CV here.

Publications

1. Thieme, Frederik, Heike Klüver, and Jae-Jae Spoon. Helping the Cause? How Female Party Leaders Impact Voter Turnout and Preferences. Conditionally accepted. British Journal of Political Science.
   [Abstract]

   Can nominating a female top candidate win over women? In light of persistent gender disparities in politics, understanding how female top candidates affect voters is crucial, yet causal evidence from real campaigns remains scarce. We address this question leveraging the unexpected nomination of Annalena Baerbock as the German Green Party's top candidate in the 2021 federal election. Drawing on a large-scale survey of nearly 22,000 citizens conducted during the nomination, we find that her nomination boosted support for the Greens -- among women and men alike. We complement this analysis with a preregistered survey experiment among 9,000 respondents that directly manipulates candidate gender to isolate its causal effect. We show that nominating a woman positively affects vote intentions. These effects are driven by a desire to promote gender equality, shared identity, issue alignment, and increased external efficacy among women. Our findings demonstrate how increasing the visibility of women in top political roles can help reduce the gender gap in politics.
2. Thieme, Frederik. Pocketbook Politics and Climate Action: How Economic Strain Reduces Support for Green Parties. Forthcoming. European Journal of Political Research.
   [Abstract]

   Why do green parties struggle electorally despite overwhelming public support for climate action? While macro-level studies suggest that green party performance is shaped by economic conditions, the micro-level mechanisms driving this relationship remain unclear. This paper investigates whether personal economic strain reduces support for green parties and reshapes climate-related political attitudes. Leveraging rich panel data from Germany (2016–2024), I combine long-term correlational analysis with a difference-in-differences design exploiting the war-related 2022 surge in consumer prices. Voters facing financial hardship consistently evaluate the Greens more negatively and shift their political attention toward inflation and economic growth, while deprioritizing climate protection. However, evidence on vote intentions is mixed. These findings contribute to debates on green party support and the distributive politics of climate action, highlighting the relevance of voters' pocketbooks and the need for green parties to convincingly address material concerns to ensure electoral success.

Working Papers

• (Not) Merely Symbolic: Reactions to Radical Right Success. Presented at EPSS 2026.
  [Abstract]

  Why does the electoral success of radical right parties (RRPs) not produce widespread countermobilization? Building on intergroup-threat theory, I argue that the crucial distinction is between symbolic and realistic threat. Symbolic threats to democratic norms and values are broadly perceived, but behavioral responses are concentrated among groups facing realistic threats to their power, resources, and physical wellbeing. I identify three such groups: Muslim communities, young women, and LGBTQIA+ individuals. Using open-ended survey data from the German Longitudinal Election Study, I apply a subcategorized keyword dictionary to track concern about the radical right across several dimensions. Young women and Muslim respondents show elevated concern, concentrated on the anti-immigration and racism dimension. Patterns for the queer community are inconclusive. A staggered difference-in-differences design shows that newly concerned voters shift toward parliamentary parties and move left across the party spectrum, consistent with pragmatic electoral responses. Placebo analyses on left-right self-placement and political interest confirm that these are strategic choices, not attitudinal shifts.
• The mobilization of young voters: Evidence from a field experiment (with Heike Klüver). Under Review.
  [Abstract]

  Can traditional campaign tools still mobilize young voters in the digital age? Despite the widespread use of direct mail in election campaigns, we lack causal evidence on whether party-sent letters influence first-time voters, an electorally crucial group whose initial vote choices can shape long-term political behavior. We address this question through a large-scale field experiment conducted in collaboration with a major German parliamentary party during the 2024 European Parliament election. Randomizing the distribution of 37,000 letters in Berlin, we estimate the causal effect of partisan direct mail on turnout and vote choice. We find no evidence of positive campaign effects on electoral participation or party support. Effects on propensity-to-vote move against the predicted direction, and a sensitivity analysis confirms that positive effects of the magnitude documented in the existing literature are unlikely given the observed data. These findings challenge the effectiveness of conventional mobilization tactics among digitally native cohorts and underscore the need to reassess established strategies for engaging first-time voters in contemporary democracies.
• The effectiveness of tailored online campaigning: Evidence from a field experiment targeting women (with Heike Klüver). Under Review.
  [Abstract]

  How effective is tailored online political advertising in mobilizing voters? We argue that appeals resonating with salient voter identities, such as gender and parenthood, should increase engagement and turnout. To test this, we conducted a large-scale field experiment with the German Green Party during the 2024 European Parliament election, randomly assigning ZIP codes to receive either generic or identity-tailored ads targeting middle-aged women. The campaign reached over 686,000 women. Using official election returns, we find no evidence that tailored ads increased turnout or vote share, with survey data revealing low platform penetration and ad recall among the target group. To distinguish between a failure of message content and a failure of delivery, we complement the field experiment with a survey experiment among German women (N=5,394). The survey experiment finds positive effects of tailored messages on propensity to vote for the Greens, particularly for care infrastructure appeals among mothers, with effects attenuating among less attentive respondents. Taken together, the evidence suggests that the null field result reflects a failure of delivery rather than of content: tailored messages can persuade when they reach their audience, but platform constraints and scarce user attention severely limit meaningful exposure in practice.
• The Shadow of Occupation: Political Support under Foreign Invasion (with Salma Mahamed). Presented at EPSA 2025.
  [Abstract]

  Does military occupation impact political support? We conceptualize occupation as an abrupt shock to the norm environment and opportunity structure, lowering the social costs of extremist affiliation and offering new incentives to do so. This allows us to consider two mechanisms: opportunistic alignment driven by material self-interest, and preference revelation among latent sympathizers with so far falsified preferences. We test these arguments using previously unused individual-level data on 19,000 members of the Danish National Socialist Workers' Party (DNSAP) before and after Germany's invasion in April 1940, supplemented by newly digitized constituency-level election returns from 1929 to 1943. Descriptively, we show a clear influx spike post invasion. A compositional event-study further shows that this increase is concentrated among older, better-educated, and higher-status individuals. A cross-level mechanism test leveraging the 1939 and 1943 elections shows that post-invasion membership surges predict subsequent DNSAP electoral gains geographically, consistent with preference revelation as the dominant mechanism. The findings show that political norm environments can collapse abruptly rather than erode gradually and offer a rare empirical window into political behavior under imposed authoritarian rule.

Teaching

All syllabi are available upon request.

• Climate Change & Political Behavior (Seminar), Humboldt University (Summer 2026)
• Experiments and Causal Inference Methods (Lecture & Seminar) together with Tim Wappenhans, Humboldt University (Winter 2025/26)
• International and Comparative Politics (Introductory Seminar), Humboldt University (Summer 2025)
• Experiments and Causal Inference Methods (Lecture & Seminar) together with Tim Wappenhans, Humboldt University (Winter 2024/25)
• In this economy? Economic inequality and political behavior (Seminar), Humboldt University (Summer 2024)
• Empirical Social Sciences: Experiments and Causal Inference (Lecture & Seminar) together with Tim Wappenhans Humboldt University (Winter 2023/24)
• Political scandals, voters' attitudes and behavior: from successful accountability to inconsequence (Seminar), Humboldt University (Summer 2023)

This website uses the minimal theme and is inspired by Shiro Kuriwaki's website, Sascha Riaz's website, and Tim Wappenhans' website.