Recent political campaigns have been based on the exploitation of negative feelings, such as fear, about the rise of immigration, a terrorist attack, the enlargement of the European Union or the economic situation. The notion that emotions can change political behavior is a well accepted one. But perhaps less is known about how emotions help parties build popularity and spread their message among the population. Are positive and negative campaign messages contagious? Which emotions resonate more with the population? This paper uses a novel approach to study the link between emotions and popularity by analyzing Twitter data during the UK 2017 GE and the Greek 2015 GE. Results show that parties can benefit from running positive campaigns as their popularity will increase faster and quicker than when they appeal to negative emotions, challenging the idea that we have entered an era of politics of fear.