David Frum was once a member in good standing of the Republican establishment — he was the guy who coined the phrase “Axis of Evil” for George W. Bush. Since Obama took office, however, he’s been questioning the wisdom of the GOP’s hard-line oppositionalism and extremism. For his efforts, he’s been booted from his think-tank sinecure at the American Enterprise Institute and scorned by Republican true believers.

Anyway, Frum is uniquely positioned to diagnose the modern right. Today he’s got a sharp review of the new book from long-time scholars of U.S. government Thomas Mann and Norman Ornstein: It’s Even Worse Than It Looks: How the American Constitutional System Collided With the New Politics of Extremism. Mann and Ornstein made a bit of a splash in April with an op-ed in the Washington Post, which concluded that “Republicans are the problem.” Mann and Ornstein are no one’s idea of partisan bomb-throwers. They’ve been studying Washington for decades are are widely respected and quoted on both sides of the aisle. But they can’t deny the obvious reality. (Unsurprisingly, the Sunday cable talk shows have shown no interest in this — it would, after all, explode their entire business model.)

Frum’s contribution is to note that recent GOP extremism can be traced not only to the internal dynamics of DC, but to the economy more broadly: