This paper develops a conceptual framework highlighting the functional and constitutional (two‐level) negotiation aspects of water governance rescaling, illustrated by the case of southern Spanish water governance reorganization for the Guadalquivir River Basin. The framework is derived from theories of institutional change and multi‐level governance. A necessary precondition for rescaling is changes in actor‐specific perceptions concerning how to best address priorities of water management through water governance. Predominant in rescaling is its coincidence with a contingent political majority of these actors enabling agreement on changes in governance conforming to existing constitutional rules for negotiation. Ultimately, in southern Spain, the constitutional setting prevented re‐scaling. It had initially been promoted by regional actors benefitting from a contingent political majority at the federal as well as at the state level. The paper highlights that, in the context of transformations of European water governance, in Spain supranational policy‐making is of low significance domestically. Copyright © 2014 John Wiley & Sons, Ltd and ERP Environment