I second the recommendations, and since political science seems to be a strong interest for him, if he is curious at all about the history of how we ended up with the Republican Party we have today, he might also want to check out "Rule and Ruin" by Geoffrey Kabaservice.
The full title of the book is "Rule and Ruin: The Downfall of Moderation and the Destruction of the Republican Party, From Eisenhower to the Tea Party", and judging from the title, it is a partisan screed. Aculady, I could recommend many books critical of the Democratic party and the current president, but this is not place for it.
