The pictures of the US Capitol attack, on January 6, 2021, represent a before and after in a country marked by the culture of political polarization. Following a presidential campaign based on misinformation and accusations of electoral fraud by Republican candidate Donald Trump, the level of maximum polarization causes a climate of social rupture. Faced with this, the Democratic candidate and winner of the elections, Joe Biden, projects a discourse of institutional stability and legality as a strategy before public opinion. Two years later, the abrupt division of the US electorate is evident, with a significant percentage of Republican voters questioning the legitimacy of the electoral process. The objective of this research is to find out the strategies of political polarization deployed by Donald Trump and Joe Biden on Twitter in the 2020-2021 presidential transition period, as well as the public’s response. Based on a general sample of 1,060 tweets, a comparative content analysis methodology with a triple approach (quantitative-qualitative-discursive) i applied, based on the study of themes, emotions, and the ability to go viral of the messages of both political leaders. The results confirm a Trump’s speech defined by polarization, misinformation and the attack on the democratic system, relegating information from his presidential administration in the last months of his term to the background. On the contrary, Biden avoids confrontation and reinforces his legitimacy as president-elect, by announcing management measures of the future government. The engagement value of the social audience on Twitter is also added, with a position of support for the winner of the elections.
