The paper analyses the political challenges and opportunities of advancing the climate change agenda in a developing country under constraints and channels imposed by divided authority at the vertical level and political fragmentation within the state. The articles focuses on historical and political institutional arrangements to approach the current framework of climate change agenda‐setting in Mexico, later analysing the potential changes to the outcomes due to the influence of an international climate change regime. On the one hand, the literature suggests that federalism poses serious limitations to government efficacy due to division of competences, and a similar argument is posed about presidentialism under a politically fragmented regime; on the second hand, transnationalism is depicted to enhance subnational state and non‐state actor leadership roles in many areas, including economic and environmental policy setting. Evidence shows that federalism and the political fragmentation of the presidential regime in Mexico has prevented the federal government from taking assertive steps to influence subnational governments, while some of the heads of politically relevant subnational governments have assumed policy leadership roles, enabled by transnational networks and the Kyoto climate change regime. This balance may change according to the nature of the post‐Kyoto regime, either strengthening the federal government if more responsibility on actions and disbursement is placed on national governments; or enabling subnational government to foster their position, if decentralized and transnational networks are strengthened. Copyright © 2014 John Wiley & Sons, Ltd and ERP Environment