This paper presents research data about features of discourses held on Twitter regarding the last presidential campaign in Colombia (2018) based on the agenda-setting theory. This case study had a quantitative research approach. The sample includes 62 Trending Topics and 620 tweets that were selected according to criteria of relevance and influence. A method of systematic content analysis was applied to gather data on sources and contents of messages using SPSS software statistical analysis. Five important findings are highlighted: 1. Traditional mass media were mainly responsible for defining the agenda on Twitter. 2. Within the context of the agenda outlined by the media, it was citizens who monopolised the discussion, thereby playing a key role in topic dissemination, candidates' visibility, framings, and assessments. 3. The main topic of discussion was the campaign debate itself rather than programmatic measures. 4. No correlation between the positioning and visibility of the candidates in Twitter and the electoral results could be observed. 5. Positive/non-aggressive tones prevailed over negative/aggressive ones.