The only "political book" remotely worth reading is Fear and Loathing on the Campaign Trail '72.
I also would recommend a book called 'Divided They Stand', by a British journalist named David English, about the 1968 election. as a 15 year old I thought it was the sh**t and even now am capable of appreciating it. unfortunately it's long out of print; I got it from a used bookstore around here at age 13 that is long, long out of business.
EDIT: a brief look around the usual places (Amazon, eBay) suggests that it's easier and cheaper to track down than I'd thought.