Opportunity or constraint for viable climate policy? Support for green protectionism amid trade-offs between energy sovereignty and climate ambition

Amid rising geopolitical tensions and left-right polarization over climate policy, high-income countries are turning to green protectionism -- combining green subsidies with import barriers -- to reshore low-carbon technology production. Yet, while linking climate spending to sovereignty over energy supply chains may broaden climate policy support among right-leaning individuals, restricting access to foreign low-carbon technologies could delay decarbonization and alienate pro-climate individuals. To date, little is known about how prospective energy sovereignty shapes support for climate policy and how it is weighed against climate ambition. Using data from a pre-registered survey experiment conducted in Germany (N = 3,407), we assess how individuals navigate this trade-off in policy preference formation, and how evaluations differ by political affiliation. We find that information about prospective sovereignty over under-diversified energy supply chains does not affect aggregate attitudes towards green protectionism, while exploratory evidence indicates that it only increases support when individuals also expect economic benefits from it. By contrast, information about potential delays to climate ambition consistently reduces policy support, particularly among individuals on the political left. These findings suggest that green protectionism is unlikely to broaden the political coalition for climate policy and may instead erode support among its core constituencies. More broadly, they advance understanding of how citizens weigh competing sociotropic and egotropic goals in policy preference formation under intensifying geopolitical competition.