With higher levels of polarization in the European Parliament (EP), mainstream groups increasingly face the trade-off between engaging and dismissing Eurosceptic challenger parties. Therefore, this article proposes a model to understand the strategies of mainstream and Eurosceptic groups in legislative work. It uses content analysis of legislative amendments to explain under what conditions these two sets of actors decide to engage with or disengage from each other. We compare two legislative packages, the more technical Circular Economy Package with the highly politicized Asylum Reform Package to assess how the choices of mainstream and Eurosceptic groups influence the survival of amendments and the success of the EP in trilogues. The comparison shows that politicization leads to more polarization and, subsequently, increases the chances that mainstream groups will collaborate with and copy soft-Eurosceptics along a left-right divide. At the same time, we also demonstrate that disengagement from Eurosceptic groups is closely related to their small size and limited resources. Finally, although the cordon sanitaire is systematically used to exclude hard Eurosceptics, it is not effective when it comes to isolating radical populist amendments proposed by soft-Eurosceptics and mainstream groups.