It appears that this summer's book is becoming Rule and Ruin by Geoffrey Kabaservice. The somewhat long subtitle is, "The Downfall of Moderation and the Destruction of the Republican Party, from Eisenhower to the Tea Party."
Only a short way into the book, I am enormously impressed with both the focus and execution of the tome. It tells a forgotten history of an ideologically mixed party, which in fact was essentially a fairly moderate party, conservative on fiscal matters, progressive on Civil Rights. Always there was within the party, of course, a right-wing. But not until the 1950's and Senator Joseph McCarthy paving the way did so-called movement conservatism gain traction.
The full story is amply and well-told in this volume by Kabaservice. His warning is extremely valuable as we now find ourselves in the position of so many other countries with two parties, almost exclusive of each other ideologically, and locked in something akin to mortal combat.
Yet this has not been America's history until quite recently. It is this division which directors of America's intelligence services are warning about. The United States, they advise us, is now threatened not only from without but within. This is a problem of the gravest national urgency and must be addressed with thoughtful and concrete actions -- and without delay.
N.B. for photo and graphic aficionados: the shadowing and fading of the above picture of the book cover is part of the original design of the cover. Actual print on the book cover is essentially quite clear.