Far right populism has been on the rise in various democracies, disrupting the cultural trend towards favoring socially progressive policies. The emergence of populist radical right parties and politicians was the result of growing attachment to authoritarian attitudes and feelings of alienation among people, specifically members of older generations. Norris and Inglehart’s cultural backlash theory describes these societal developments and conditions over the past decades that led to public support for far right populism. This research examines the mainstream discourse in a society as an additional component that answers the question: What caused the recent electoral success of populist radical right parties in Western democracies? The Overton Window, a concept that constructs a frame around the accepted opinions in a society with the ability to move, indicates a country’s mainstream discourse. I argue that the cultural backlash caused the Overton Window to change, thereby allowing populist radical right rhetoric to normalize in national politics and mobilize a voter base. The two countries under review that have experienced extreme cases of far right populism in recent years are the United States and Germany. Through data collection on the positions of political parties in each country over the past 35 years, I measure the development of the mainstream discourse. My results show an expansion of the Overton Window in both cases and indicate that through the emergence of populist radical right parties answering to the new mainstream discourse, authoritarian attitudes were acknowledged and normalized, which triggered the parties’ electoral success.