The proponents of state sovereignty—the confederalists—were challenged by some less radical federalist delegates who argued that only the nation could be sovereign. Because these men stressed the need to endow the national government with sufficient power to sustain national interests, they are often mistakenly considered centralists. Servando Teresa de Mier, their outstanding spokesman, argued that people wrongly considered him a centralist, an error that arose from an unnecessarily restrictive definition of federalism. He indicated that federalism existed in many forms: the Netherlands, Germany, Switzerland and the United States were federations, yet each was different.