What is the main conflict in Foundation's Edge by Isaac Asimov?

FOUNDATION'S EDGE looks at the Milky Way Galaxy halfway through the timeline of the Seldon Plan, as ambitious rulers of the First and Second Foundations vie for total control. The reclusive people of Gaia, who share a common mind, arrange a rendezvous and leave it to intuitive protagonist Golan Trevize to decide the Galaxy's future.