Understanding citizen’s European and national attachment is crucial to both researchers and practitioners dealing with problems of social cohesion, European integration, and the perceived legitimacy of decision-making processes within democratic institutions. Yet, the measurement of the national identities of European citizens remains a contested issue in the scholarly literature. Despite its widespread use in public opinion surveys, the so-called ‘Moreno question’ has been criticized as it forces respondents to choose between bipolar, competitive categories of national identities that may not fully capture the complexity of national political identities (Bochsler et al., 2021; Levy, 2014; Sinnott, 2006). Through this paper we explore the consequences of an under-discussed problem of Moreno-style questions: the aprioristic definition of the two possible national identities between which respondents are asked to position themself. The eurosceptic turn of many stateless nationalist parties in Europe after the early 2000s (Huysseune, 2010; Massetti & Schakel, 2021) underscores the limitations of this methodological approach, as it remains blind to citizens who hold strong national sentiments but identify with neither European institutions nor their nation-state. Casting this distinctive group of citizens aside in the basket of non-respondents may introduce a significant bias in empirical analyses. In this communication, we will explore the patterns of nonresponse to the Eurobarometer question on national and European identities among voters of both Eurosceptic and Europhile stateless regionalist parties and discuss the theoretical and methodological implications of our findings.