Browsing Gamespot's screenshots section, there's some which shed some light on the interface and gameplay -
The Government Panel, for instance (i'm guessing this shows the democratic system) -
Here, we can see the Prime Minister/President, and beneath his ministers - the Foreign Minister, Finance Minister, Justice Minister, the Minister for the Army, and the Minister for the Navy.
And there's also mention there of Popularity and elections.
EDIT: Whoops, can someone move this to the Empire: Total War thread please?