Saga What real world governmental organizational structure does the Galactic Republic most resemble?

This may end up needing to go to the expanded universe section but I thought I'd start it here for all Saga die-hards to start off the conversation. Another thread got me wondering exactly what real world governmental organization the Galactic Republic most closely resembles. It seems more loosely united than the states within the United States, but to me, it seems stronger and more integrated than the UN. Perhaps it's closer to the European Union (independent states united mostly by economic cooperation but with some rules that govern all the countries). Another option could be NATO.

Some other questions I'm curious about: How much sovereignity does each member planet in the Galactic Republic have? In what ways can the Galactic Senate and the Chancellor control or limit or regulate the conduct of an member planet? And what responsiblity does one member planet have to another member planet?

Any ideas?

 

The PT senate felt more like the UN to me. Sovereign "states", with the big ones able to veto any resolution they don´t like. The Chancellor seemed to have a bit more power (in theory) than the UN equivalent though. I wouldn´t say UE because economics aside, politics are usually left to each country.

 

Ancient Rome

From Republic to Empire