“We define populism as a platform that promotes policies based on a mis-specified model of the world — a simple alternative worldview. Voters’ trust in the traditional political class evolves over time, depending on the performance of mainstream politicians while in office. Crucially, political distrust increases voters’ susceptibility to the alternative worldviews offered by populists. In turn, the threat of populist success disciplines traditional politicians encouraging better performance. We study when and how populists and their alternative narratives gain traction or recur, and we examine their long-run effects on voter welfare. A key feature of the model is the feedback loop between distrust and alternative truths: political distrust persists, making voters more receptive to populists even when traditional politicians improve their performance. This dynamic gives rise to a low-trust trap, where trust in mainstream politicians never fully recovers, and cycles of populist and traditional rule repeatedly emerge.