If I were to start this RP, I would have each of the Authors create a politician who would be either a senator or representative in Congress. It might be better just to limit it to one house or the other. Since there are only two senators from each state, the senate would be the best place to start. Then once everyone has created a character, we then ask for volunteers to run for President.
The first rounds of the IC would be the election. US Politics are all about the Democrats and Republicans, but I would open it up to the Tea Party, the Libertarians, the Green Party, the Socialists and whatever other minor party is out there. Those candidates running for president could then choose their own VP/Running mate from the group of us. Once we the people have chosen POTUSA and VP, the Pres could then fill the primary secretary slots with us.
Once the new administration is established, then I would throw national and international issues at the new administration to deal with. As a Senator, we could the draft and recommend legislation to be discussed and potentially passed by the senate and the House of Representatives.
I write this because secretly, I would love to do this. The problem is, I am in four or five other RPs, have four young children and am about as busy as a one armed paper hanger. I would not be able to do this RP the justice it deserves. My posts/updates would go 2-3 weeks before I could respond. You guys would be all like, "Where the hell is Gunther?" I would say, "I'm here, but I haven't got time to respond to this yet." They you all would be like, "Frig this, I'm going back to my anime/steampunk/Harry Potter RP."...and so it would die. :(