This study aims to analyze the correlation between radical-left Euroskeptic (RLE) activity and European Union (EU) trade policy by focusing on the Transatlantic Trade and Investment Partnership (TTIP). At the beginning of TTIP negotiations, the agreement was not high on political agendas and was not a major concern within European society. Thus, its salience was low. This initial lack of interest stemmed from the fact that the TTIP, as an economic and technical issue, did not draw public attention. This study shows that RLEs profoundly affected public opinion on the TTIP by increasing its salience during the European parliamentary elections in 2014 in France and Germany. Second, RLEs involved social actors and non-governmental organizations in anti-TTIP campaigns and channeled European anxieties into the STOP TTIP European Citizens’ Initiative. Third, RLEs used this proposed agreement between the EU and the United States to increase polarization within European society and ideological cleavages within the European Parliament. Finally, we can assume that an anti-TTIP campaign promoted by radical-right Euroskeptics would have had different drivers. Thus, my findings have implications for understanding the correlation between RLE activity and the politicization of EU trade policy, and they suggest some avenues for future research.