In the last decade, there has been a lot of academic interest in the impact of new methods that political parties use in their campaigns, mainly social media sites (SMS) (Vergeer et al., 2011). Twitter is one of the most influential SMS for political campaigns worldwide, so it has been used in several of these studies (Ceron et al., 2014; Ceron & d’Adda, 2016). This study aims to measure the impact of negative and positive campaign strategies used by the main Portuguese political parties and their respective political leaders, on Twitter, on electorate voting intentions measured by several polls carried out during the past five Portuguese general elections.