Bloc Politics: Investigating Party Support and Electoral Volatility in Welsh Multilevel Elections

Brexit has reshaped patterns of electoral behaviour in Britain. Voters increasingly perceive political parties as divided into two blocs (a left-liberal bloc and a right-conservative bloc) and recent research shows that voters now switch primarily within, rather than between, these blocs. However, far less is known about whether and how this bloc structure extends to devolved elections. We address this gap by examining voting behaviour in Wales, using survey data from every devolved election between 1999 and 2026. We argue that Welsh party competition has long been structured around two blocs (a Welsh/left bloc and a British/right bloc) with voters predominantly switching within these blocs. Our analysis examines whether patterns of within- and between-bloc switching have changed over time, and whether these dynamics have been reshaped by Brexit. These findings have important implications for how we understand electoral competition and party alignment in Welsh politics.