The core idea of party moderation implies a party's embracement of open worldviews that do not contradict democratic principles and compromise with other actors. While much has been written on the factors leading to the moderation of Islamist parties, little is known why such moderation does not sustain or why de-moderation is likely to follow afterwards. In this paper, I re-evaluate the existing theories of moderation and apply the method of process-tracing to establish a new causal mechanism that explains the transitions between the stages of pre-moderation, moderation and de-moderation of an Islamist party. I argue that the party's ownership of a specific issue, which is the issue of ‘insubordination to state repression', is the main causal trigger for the transition to the stage of moderation. The ownership of this issue in electoral campaigns helps the party to attract a heterogeneous group of supporters who have either been the victims or the critics of state repression. When the repressive acts of the state, yet, vanish from the political stage, the Islamist party also loses the ownership of this salient issue that unites this diverse body of supporters. The party instead starts using reward and punishment mechanisms to sustain the loyalty of its electoral supporters. This depicts the transition from the stage of moderation to the stage of de-moderation. To illustrate the proposed explanation, I focus on the case of the AKP in Turkey and bridge interview data conducted with the AKP and opposition party activists in the years of 2007, 2011 and 2018. Interview evidence is complemented with the media statements of public opinion leaders in the moderation and de-moderation stages of the AKP.