Class, ethnicity, age, or education:what characteristics determine citizens' sense of political commonality?

We know from election studies which demographic characteristics best predict vote choice, but we know far less about how citizens perceive their similarity to one another in terms of these characteristics. Previous research suggests that such perceptions may be crucial for the politicization of social identities and the emergence of political identities. I present results from a novel measurement strategy where respondents are presented with the profiles of two fellow citizens, including several demographic attributes. Respondents are asked which of the two they perceive themselves to have more in common with in terms of politics. Respondents' implicit trade-off of different demographic similarities allows me to measure the relative strength of their perceived political similarities. I find an important role for shared ethnicity, noticeably surpassing shared social class, age and education. Finally, I find that shared ethnicity receives substantially more weight among 2017 Conservative and 2016 Leave voters than among Labour and Remain voters.