„A United States of Europe is possible as an agreement between the European capitalists … but to what end? Only for the purpose of jointly suppressing socialism in Europe“

— Vladimir Lenin
„Two centuries ago, a former European colony decided to catch up with Europe. It succeeded so well that the United States of America became a monster, in which the taints, the sickness and the inhumanity of Europe have grown to appalling dimensions“
— Frantz Fanon
„We must build a kind of United States of Europe.“
— Winston S. Churchill
„The times when the centre of gravity of political development and the crystallising agent of capitalist contradictions lay on the European continent, are long gone by. To-day Europe is only a link in the tangled chain of international connections and contradictions.“
— Rosa Luxemburg
„Plausible as the idea of the United States of Europe as a peace arrangement may seem to some at first glance, it has on closer examination not the least thing in common with the method of thought and the standpoint of social democracy... At the present stage of development of the world market and of world economy, the conception of Europe as an isolated economic unit is a sterile concoction of the brain. Europe no more forms a special unit within world economy than does Asia or America.“
— Rosa Luxemburg