Spatial contagion and party competition on environmental issue salience

This study explores the dynamics of party competition on issue salience, taking the environment as a case study. We integrate concepts from saliency theory, issue ownership, and the “riding-the-wave” approach with a novel concept: the spatial contagion effect. This effect posits that a party's emphasis on environmental issues spills over to rival parties, amplifying the riding-the-wave phenomenon. Employing spatial regression analysis of party manifestos and survey data, we demonstrate the existence of this contagion effect. Interestingly, the effect is moderated by the presence of green parties. When no green parties compete, the contagion effect strengthens the riding-the-wave phenomenon. However, the effect weakens when green parties are present, as they already “own” the environmental issue.