It’s an image that still shocks in its feral intensity: On July 14, 1964, supporters of Barry Goldwater, the arch-conservative senator from Arizona whom the Republican Party was preparing to crown as its presidential nominee, unleashed a torrent of boos against New York Governor Nelson Rockefeller as he spoke at the party’s national convention in San Francisco.

More than half a century later, Goldwater’s army of conservatives from cookie-cutter Sun Belt subdivisions howling their discontent at Rockefeller—the embodiment of the GOP’s centrist, East Coast establishment—remains a milestone in the right’s conquest of the party. The atmosphere was so heated that Jackie Robinson, who was a Rockefeller supporter, nearly got into a fight on the floor with a Goldwater acolyte from Alabama.

What’s less remembered is why Rockefeller, who had lost the nomination to Goldwater, was standing behind the lectern in the first place: to speak in support of an amendment to the party platform that would condemn political extremism. The resolution repudiated “the efforts of irresponsible extremist organizations,” including the Communist Party, the Ku Klux Klan, and the John Birch Society, a rapidly growing far-right grassroots group obsessed with the alleged communist infiltration of America.

The resolution failed, which testifies to the GOP’s long-standing reluctance to draw a bright line against the extremists who congregate at its fringes. But the fact that such a resolution was debated at all—in such a visible venue, with such high-profile advocates—also says something about Republicans today: In the past, the GOP had a stronger core of resistance to extremism than it’s had in the era of Donald Trump, QAnon, the Proud Boys, and Marjorie Taylor Greene.

“There were a lot more Republican leaders, and their constituents, who attempted to push back then than there are now,” says Matthew Dallek, a political historian at George Washington University and the author of an upcoming history of the John Birch Society. “To a large extent, the people who have inherited the Birch legacy today, I think, are more empowered [and] more visible within the Republican Party. There is much less criticism; there is much less of an effort to drum them out; there is a much greater fear of antagonizing them. They are the so-called Republican base.”

The question of how Republicans deal with the extremists in their ranks is now more urgent than perhaps at any other point since the Birch Society’s heyday in the 1960s. So far, as Dallek notes, the party has done little to uproot them. Representative Kevin McCarthy, the House GOP leader, this week reportedly pressured Greene to apologize for past statements that were racist, anti-Semitic, and encouraged violence, and to relinquish one committee assignment. But ultimately the GOP chose to take no action against her and instead criticized a floor vote Democrats scheduled for today to remove her from all her committees. (By several accounts, many of Greene’s GOP colleagues even gave her a standing ovation after she addressed a caucus meeting yesterday afternoon.) Nor have McCarthy and other GOP leaders shown any interest in acting against the House members who promoted or spoke at Trump’s rally ahead of the January 6 attack on the Capitol. And while GOP Senate Leader Mitch McConnell and some other Senate Republicans have criticized Greene—a relatively easy target—almost all have signaled that they will not vote in Trump’s upcoming impeachment trial to impose any consequences on him for his role in fomenting the attack.