It is a truism to state that the Transatlantic Trade and Investment Partnership (TTIP) is a politicized issue, yet the explanations that account for this politicization are mostly singular in nature. In this paper I add to this understanding theoretically and empirically by presenting a broad analytic framework that puts TTIP at the intersection of two evolutions. There is, firstly, a longer-term trend of increasing political authority of (European) trade policy that is (at least by several organizations and citizens) not considered legitimate. I argue that TTIP is an extension and an intensification of this perceived authority-without-legitimacy trend. Secondly, the particular explosive situation that has occurred since 2013 is furthermore the result of a specific combination of a favoring political opportunity structure, combined with pre-existing mobilization resources that have facilitated a large mobilization by civil society organizations. This explains the spike of politicization that is attached onto this longer term trend. Relying on several exploratory interviews, I try to uncover the determinants in the different categories