This is a May 1, 2008 document issued from the world's foremost stink tank--The Council on Foreign Relations:

International Institutions and Global Governance Program
World Order in the 21st Century
A New Initiative of the Council on Foreign Relations

Two excerpts:

"In each of these spheres, the program will consider whether the most promising framework for governance is a formal organization with universal membership (e.g., the United Nations); a regional or sub-regional organization; a narrower, informal coalition of like-minded countries; or some combination of all three."

"...the country’s longstanding tradition of liberal “exceptionalism” inspires U.S. vigilance in protecting the domestic sovereignty and institutions from the perceived incursions of international bodies. Finally, the separation of powers enshrined in the U.S. Constitution, which gives Congress a critical voice in the ratification of treaties and endorsement of global institutions, complicates U.S. assumptions of new international obligations."

You can read the entire document and then, as they like to say in sportscasting, "You make the call."