Political cleavages: What drives the alignment between identities, attitudes, and party support among individuals?

Researchers have long emphasised how cleavages can structure political competition in states. These political cleavages represent the alignment of different social groups, with different beliefs, and distinct political representation. Extensive research has discussed why these cleavages emerge within society, but far less research has explored how these cleavages emerge within individuals. This is important because the alignment between group identities, attitudes, and party support can lead to greater polarisation and out-group hostility. Consequently, I examine how political cleavages develop within individuals in one specific case study: the Brexit cleavage in Britain between 2014 and 2024. Using British Election Study Internet Panel data, I explore the alignments between (national) identity, (European) attitudes, and (Conservative) party support. Overall, I find that there was greater alignment between identities, attitudes, and party support after the 2016 EU referendum, but this alignment was not driven exclusively by one dimension over the others. These results challenge classic assumptions that identities guide politics, demonstrating that the relationships between identities, attitudes, and party support can be reciprocal. This is important for researchers and political elites, who want to understand how these factors change over time.