Do Away with National Sovereignty

It's been suggested, and I concur, that the jump in my "model" from municipality to world is too large; there needs to be an intermediate step to deal with issues that are too large for a couple or several municipalities to handle, but not world level problems.

Looking at things from a different perspective... Sovereignty: 1.)Supreme power or authority; 1.1.)The authority of a state to govern itself or another state; 1.2.) A self governing state.

So, I ask this: could an administrative body, answerable to a large region (say the size of a country) exist and function without claims of sovereignty? It seems that municipalities do so. Cities make no claim to exclusive or supreme power. The state (as in North Carolina) governs the same area, at the same time, and indeed, often governs what the city does.

Add to that a body that serves as problem solving enabler rather than policy setter (as outlined in my original model) and move that to a large regional administrative body. A body that assembles experts and stake holders from a large area to solve problems affecting a large area.