This study examines the relationship between politicians and managers in a Swedish city. The context is a collaborative organization responsible for drafting and implementing the vision and strategies for a city organization, and for future development of the downtown river area. The article examines the efforts of city managers to manage the relationship with city politicians. We illustrate how the managers strive to manage an appropriate ‘arm’s-length’ relationship with the politicians by navigating in and out of the ‘purple zone’ of the politics–management interface, and how the context of collaborative organizations seems to increase the amount of time public managers spend in this zone. Points for practitioners This article illustrates the relation between managers and politicians in a city organization. We use the concept of the ‘purple zone’ to show how managers’ and politicians’ work is blurred in a collaborative organization, and how this context seems to increase the amount of time public managers spend in this zone. This implies that managers often take on a responsibility for solving complex issues.