Well, this genre actually defines itself as well. Everything that deals with politics, be it through parties or terrorism, is somehow political motivated, involved in politics and therefore deserves this genre.
I can name All About My Romance as an example for a political genre where people within the parliament are involved - it actually evolves around two politicians!
On the other hand we have IRIS. The organization of the same name is definitely involved in politics but it's a secret organization so it's close to an underground group.