This study investigates why social movements either form political parties or remain extra-parliamentary. I hypothesize that the availability of suitable political representation critically shapes these trajectories. Through a comparative analysis of the German Greens and the far-right PEGIDA movement and process tracing approach, I examine the organizational evolution of the German Greens and PEGIDA. Findings reveal the Greens formed a new party to address an unrepresented ecological agenda. In contrast, PEGIDA, facing a similar anti-immigrant gap, fused with the transforming Alternative für Deutschland, obviating its own party formation. Cross national evidence from Manifesto Project Data complements these findings, illustrating that representation gaps are closed following the entry of Green and far-right parties. This work contributes by demonstrating that representational gaps are not only filled by new party emergence but also by symbiotic absorption into existing parties, offering a more nuanced understanding of institutionalization and party system adaptation.
Fırat Kimya (Thu,) studied this question.