Immigration has been considered critical for the emergence of a new cleavage in the European Union that pits the winners of globalisation against the losers. Ample research has demonstrated the social structure and the organisational base of this new cleavage. So far, however, there is no study showing that the rise of new parties is also associated with a stronger political identification of individuals with issues that these parties promote – a key feature to speak of a cleavage in the tradition of Lipset and Rokkan. In this paper, we provide systematic evidence on whether immigration contributes to the collective identification with the new cleavage on the micro-level. We show that an increase in immigration is strongly associated with this process and contrast our argument against alternative explanations that scrutinize the dealignment of individuals and political parties. We analyse a dataset of about 600 000 comments made on Facebook below articles of regional German newspapers using topic models to add to the debate about the emergence of new cleavages in Europe.