In the debate on democratic backsliding, academic interest has mainly focused on governments’ EU agenda and the interplay of governmental versus EU actors. Our analysis broadens this focus, asking how opposition parties approach important aspects of European integration in the two countries and how they respond to government action. Previous research identified differences in opposition party behaviour in Poland and Hungary. These were rooted in the individual parties’ political positions and in the opposition party frame – the level of polarisation, fragmentation, and party dominance. With regard to EU issues this approach should be further deepened with a qualitative dimension. The paper asks how opposition parties develop their argumentation in concrete EU-related and debated issues by investigating the party narratives in one important parliamentary debate: the evolution of the Own Resources Decision in the Polish Sejm and the Hungarian Parliament. On what grounds do government versus opposition conflicts emerge? The reading and textual analysis of the parliamentary debate highlights whether the opposition parties use pragmatic or identity arguments in developing their standpoints and how they connect to the government’s perspective. The findings will be instructive in three respects: Given the general EU sympathy in both countries, the analysis clarifies whether opposition parties regard EU-related issues as an important terrain of conflict with the government – that is a dimension of electoral competition. Given the exceedingly troubled connections between the EU and the two countries, the analysis highlights whether opposition parties speak with the same voice or are divided, thus what outcomes might be expected in future EU-related political conflicts. Given the former findings on substantial differences in opposition behaviour between Poland and Hungary focusing on the institutional context, this new approach extends our knowledge: either add to the sources of differences or modify the conclusions of former research.