We have a few political structures here and there... but I'm afraid no official 'parliament' as such or a direct executive.
There's of course the Prime Minister and President who head all the various public bodies and state services, ranging from the police departments to passport control (CMB) and the judicial system.
I guess you could take each of the heads of the different government bodies as being representatives of one aspect of the city/country as they're all accountable employees.
There's also the Argonath RPG United Nations, though its concept has changed slightly and in part now acts as a mediator between the various different groups/clans/organisations in the community. Though... for the time being... I believe it's mostly been changed to accommodate the SA:MP side. I am not sure on progress, but of course for it to be successful that's not right and it would have to be as inclusive and relevant as possible.