This is a good book and is well worth reading if you are interested in the recent history of the Republican Party (and let's be honest, who isn't interested in that question these days?).
However, I do need to bring readers' attention to the fact that it is not the most reliable book ever published. In the two instances in which I saw a detail in the book that was so juicy I wanted to know more about it, following the footnotes revealed that Popkin was either misinterpreting the source or attributing to it information it did not contain.
First, on page 201, Popkin claims that the conservative activist Phyllis Schlafly coined the term "Eastern Establishment" to refer to the Wall Street wing of the Republican Party. His footnote refers to David Blake's 2016 book Liking Ike. Consulting this book, we find no such claim. Indeed, the phrase "eastern establishment" does not appear in the entire book. The claim also does not appear in Donald Chrichtlow's academic biography of Schlafly. As far as I can tell, Popkin is the only one to claim it, and the evidence he offers does not support his claim. It's hardly implausible, and I, at least, can't disprove it, but Popkin gives us no reason to think it's true.
Second, on page 44, Popkin claims that "The year 2010 marked the first time that conservative groups spent more money in primary campaigns against incumbent GOP representatives and
senators than against Democrats in the general election." This is a very significant claim. In his footnote, he cites Paul Blumnethal's article "Citizens United, McCain-Feingold Fueled Congress' Shutdown Politics" on the Huffinton Post. The only part of that article that could be construed to support Popkin's claim is the following passage: "Campaign finance data shows that the majority of the independent spending in Republican primaries in 2012 came from the same insurgent groups behind the shutdown strategy: the Club for Growth, FreedomWorks, the Senate Conservatives Fund, Senate Conservatives Action and the Tea Party Express. These groups spent $17.9 million on last year's primary campaigns or 54 percent of all money spent in Republican primaries."
But this sentence does not make any claim at all about spending in the general election. And
$17.9 million does not come close to a majority of expenditures by conservative groups in the general election. Two Karl Rove-led groups and the Chamber of Commerce together spent nearly $60 million on the general election. In this case, we can say with confidence that Popkin's claim is simply false.
Now, any book of this size will have *some* errors of this type, particularly as publishers have slashed copy-editing and fact-checking budgets to the bone. But, it is not at all the case that I have gone through footnote after footnote looking for something wrong. Rather, in both cases where I wanted to track down the source of a claim (because I wanted to use it in my own writing!), I have found that the sources do not support the claim. That does not inspire confidence.
In sum, I recommend reading this book. But I also recommend double-checking any information you take from it.