Paul Krugman thinks the revolutionary GOP of 2020 already existed in embryo after 9/11. Is he right?
Not exactly. It is true that the party led by George W. Bush was religiously wedded to tax cuts and deregulation, regardless of the circumstances; that, obviously, has not changed. Bush also used culture war tactics to get re-elected in 2004. The current state of the GOP, however, is more the product of his failures than his successes.
The CDs and the PBPs were in charge during the Bush years; the Reactionaries just provided the votes and kept quiet. The Iraq War and the Great Recession completely discredited the CDs, in the eyes of the Reactionaries. The GOP establishment lost control of the rank and file, and the rest is history; today, Donald Trump is the establishment, and anyone who crosses him is toast.