Green Mars by Kim Stanley Robinson
Hugo Award winner.
This is the second book in a trilogy, it follows after Red Mars. Reading this book without first reading Red Mars may be challenging.
The story begins some years after the end of Red Mars. Again, the story is told from the perspective of a particular character, which individual that is changes from section to section. Again, it's a long book with lots of material covered - this is not for a reader in the mood for fluff or a quick read. Even readers who like the book as a whole may find some parts slow going.
Politics was a significant thread in Red Mars, but here there are parts where the organizing, strategies, conflicts and alliances, implementations and all the other concrete aspects of political work are described in greater depth and length. This partly has to do with the process of putting together a new government on Mars, with various groups and agendas trying to influence the outcome.
There is also the formation of a political underground movement and its efforts to build a network throughout Martian society.
It's done in a reasonably realistic manner. Certainly, this is not the typical story of the good guy gathering the right threads together and becoming the pivotal political personality or similar fantasies. There are real people whose point of view is deeply rooted, making it disinclined to change. It's not all pretty or intellectual or free of frustration. A number of differing positions are portrayed without all but one being a cardboard figure to be knocked over. If not 100% realistic, it is probably far closer than most fiction.
Partly because we are getting the story through the thoughts and experiences of this or that individual character, there can be real identification (or at least familiarity with) the major characters. Also the dynamics between the characters contributes to the quality.
Politics is by no means all that is happening. Over the decades covered by this volume terraforming advances considerably. (So much so that even the author admits it takes place in a fraction of the time that would actually be required.) There is much to see and much technology to be covered. This is an area where we see Earth's corporations heavily involved. Mars is a planet in transition, and that's a fascinating process.
At the same time Mars is being changed to be friendlier to Earth-life, Earth is in increasing trouble. Eventually, this reaches the point Mars once more declares its independence. And that's the beginning of a whole new phase - which will be explored more in the third book.