Do political parties respond to rival parties’ environmental strategies? There is an ongoing debate among practitioners and scholars about the drivers of parties’ policy positions. Yet, existing work has not, so far, fully taken into account the spatial interactions of party strategies. Current empirical efforts based on simple ordinary least squares fail to honor these complexities. This article addresses this shortcoming by examining how parties adjust their environmental positions in response to rival parties’ environmental strategies. In particular, I argue that parties are not affected by the strategies of all their competitors. Only green parties' electoral success pushes parties to emphasize environmental issues. Spatial-econometric analysis of parties’ election policies about the environment from European countries between 1980-2020 empirically establishes that among their competitors, only electorally successful green parties pressure parties to adapt environmental positions.