Coal-fired power generation is the single most important source of carbon dioxide emissions in many countries, including Germany. A government commission recently proposed to phase out coal by 2038, which implies that the country will miss its 2020 climate target. On the basis of a choice experiment that assessed 31,744 hypothetical policy scenarios in a representative sample of German voters, we show that voters prefer a phase-out by 2025. They would uphold their support for greater climate ambition up to an additional cost to society of €8.5 billion. Voters in Rhineland and Lusatia, the country’s main coal regions, also support an earlier phase-out, but to a lesser extent than voters in other regions. By demonstrating that political decision-makers are more reluctant than voters in overcoming energy path dependence, our analysis calls for further research to explain the influence of particular stakeholders in slowing energy transitions.