Contrary to movement myth, Buckley did not “purge” the Birchers from the movement in the 1960s. National Review articles in 1962 singled out the Birch Society’s founder, Robert Welch, for personal condemnation while sparing ordinary members of his organization. (A more full-throated attack on the group followed three years later, but only after Goldwater’s defeat.)

Goldwater, too, criticized Welch personally — but went no further. His campaign was powered by best-selling tracts like Phyllis Schlafly’s “A Choice, Not an Echo,” steeped in the Birchers’ baroquely paranoid style. A who’s who of the hard right, including the anti-Semite Gerald L.K. Smith, enthusiastically supported his candidacy, and the campaign did little to disavow them.

Even the party establishment that resisted Goldwater’s nomination blanched at calling out extremism. A proposed platform plank at the convention denouncing extremism and explicitly naming the Birch Society failed to find support even from Dwight Eisenhower and George Romney. By the early 1980s, long into the Birch Society’s decline, Republicans would feel less reason than ever to hide or apologize for engaging Birchers; the Society’s magazine, The Review of the News, featured interviews with the likes of Dick Cheney and Chuck Grassley.

The next generation of conservative movement activists, including Paul Weyrich (a key mentor of Newt Gingrich), Morton Blackwell and Richard Viguerie, adopted a more pugilistic approach that brought together radical and mainstream elements on the right. In the 1970s, they avoided traditional Republican small-government political appeals in favor of mobilizations over busing, abortion and gay rights while courting the segregationist George Wallace’s followers and brokering a fateful alliance between Christian evangelicals and the Republican Party.

The New Right formed think tanks, advocacy groups and political action committees to do the work they didn’t trust the formal party to do. Parties “are no more than instruments, temporary and disposable,” declared the Maryland congressman Bob Bauman at 1975’s Conservative Political Action Conference.

This troublemaking activism irked party officials like Ronald Reagan’s first Republican National Committee chairman, Richard Richards, who called the outside groups “loose cannonballs on the deck of a ship.” But their approach eventually came to dominate, thanks to the expanding right-wing media ecosystem, primary voters, and direct-mail fund-raising dollars. The refusal to police boundaries evolved from an ethos to a structural feature of the political world built by the Long New Right.

For decades, the Long New Right has depended on buy-in from moneyed interests within the Republican coalition. The grass-roots right may have disliked the plutocrats’ economic agenda, but they repeatedly accepted it to gain access to power. For their part, the plutocrats may have regarded the New Right as uncouth and their social agenda divisive, but they, too, preferred it to any available alternative.