The purpose of this chapter is to shed light on the interrelationships that exist between politicians’ Twitter agendas, news websites agendas and public agendas at the first level during the 2019 Greek Parliamentary elections for the two front-runners of the elections, Kyriakos Mitsotakis and Alexis Tsipras. Three researches were conducted to assess the issues agendas of candidates’ tweets, news websites coverage as well as the issue importance of the public for an 18-day period prior to the elections. At the issue level, although Twitter and media agendas align more, they are distinct from public agenda. Overall, Twitter proved to be an ineffective tool for influencing the news websites and public agendas during the 2019 Greek Parliamentary elections with online media agendas being slightly more powerful. Moreover, the public agenda did play a role in shaping Twitter as well as media content but in a counterbalancing manner. In addition, this study confirmed that agenda building and setting dynamics at both levels vary based on the issue and candidate being analysed.