The growing influence of regional governments in shaping climate policy and driving the renewable energy transition in multilevel democracies like Spain provides incentives for parties in favor of decentralization to emphasize these issues. Recent research has shown that such parties act as climate pioneers at the regional tier of government, driven by their desire to assert stronger subnational authority. To investigate these dynamics at the national level, this article examines the manifestos of the parties that won seats in the 2016, 2019, and 2023 Spanish national elections. The empirical findings suggest that parties are more likely to prioritize climate change and the renewable energy transition if they are pro-decentralization. By emphasizing how multilevel governance strengthens these priorities through party competition and the quest for regional autonomy, this article fills an important gap spanning decentralization and policy preferences related to climate and renewable energy.