This paper generalises the standard cartel formation game for the provisioning of a public good by allowing for supporters. Some players may not want to join a coalition that jointly provides a public good. Still they might want to support the coalition to set incentives for others to join. We show the existence of stable coalition structures with support. Support increases the size of the coalition and the amount of the public good provided.
JEL classification: H41, C78
Keywords: Public goods; coalition formation; cartel games; club theory; international environmental agreements