The main purpose of this article is to analyze whether agreement and disagreement expressed by participants in political discussions on social media influence the general process of political talk online and its outcome. This study also shows what nature of disagreement expressions prevails in political discussions on the second impeachment of D. Trump on Facebook platforms of politically polarized American mass media. The investigation is mainly based on concepts of deliberative democracy and public sphere formulated by J. Habermas, systemic approach to deliberative democracy proposed by J. Mansbridge. To achieve the goal of study, the authors use content analysis with such categories as opinion expression, interactivity, agreement and disagreement. The article concludes that agreement and disagreement expressed by participants in online conversation have no strong impact on the whole process and outcome of discussing on social media as their extents are minor, but they may influence inner processes of political talk online in different ways. As research revealed, there can be two ways: 1) a certain group of like-minded people is formed that allows to increase a level of interactivity and number of new participants in a discussion thread as people develop thoughts of each other by agreeing and adding new justifications; 2) two and more people with polarized opinions disagree with each other and attract more attention to their discussion thread that raises a level of interactivity. Disagreement in American online discussions on suggested theme can be characterized as more likely civil and justified rather than uncivil and unjustified. It means that such kind of disagreement does not have a destructive impact on political conversation and gives an opportunity for true and genuine deliberation.