Only recently have scholars turned their attention to the connection and interplay between protest mobilisation and electoral politics – often with mixed findings. This manuscript contributes to the growing field by exploring the extent to which political parties respond to protests in their parliamentary questions, and how this responsiveness might be affected by the existence of institutional allies, i.e. political parties with an ideological affinity to the protests and a shared set of goals. On the one hand, institutional allies can represent an electoral alternative for voters who deem the protests’ issue important, creating a potential electoral backlash for parties who remain unresponsive. On the other hand, responding to protest mobilisation in the presence of institutional allies can also strengthen the institutional allies due to their strong issue ownership – leaving parties with little choice but to remain silent. The empirical analysis examines two ideal types of institutional allies – environmental parties and anti-immigration parties in Germany from 1975 to 2020. By using a regression discontinuity design and mixed methods to assess the effect of protest mobilisation in parliamentary questions, the manuscript addresses some of the long-standing methodological concerns of research on the consequences of protests and social movements.