[member="Wrath Hardin"]
Political ventures generally end up in disaster at one point or another, unfortunately. The causes for this, taken from past examples, are many, from the IC unwillingness to wage less but Totaler Krieg, OOC view of such maneuvers as "Too Complicated, we're only here to write stories, not become politicians/lawyers/etc" to the simple apolitical nature of writers and / or characters. The hardest part in this won't be enforcing the Convention through the Galaxy, because there is a 99.95% chance that it will never get to the point where it will even be on the negotiation table. The issue would be getting people either interested in partaking in such a thing, and not start shagging or killing each other in the conference room, or getting people from other factions interested in participating in things like this.
Most Major faction heads have threads and issues to deal with, both IC and OOC, that their drowning in it, and without their push, most people will simply ignore it. if anything, I suggest going at it one pace at a time. Start a minor faction, get people interested in the politics side of things to join up and help you. Create a planet to use as a home base of operations, and use that to set the stage for local political based stories. Get people comfortable with this sort of writing one at a time, get major, keep increasing your numbers, try striking IC deals with other minor factions, then probe the majors and only then, if everything so far had succeeded, attempt a galactic wide convention. Until then, I'm afraid, you will mostly be disappointed.