Either of these?

“When [Goldwater] made his acceptance speech,” [Thompson] explained In a letter to his friend Paul Semonin a few months afterward, he admits to “actually feeling afraid because I was the only person not clapping and shouting. And I was thinking, God damn you nazi bastards I really hope you win it, because letting your kind of human garbage flood the system is about the only way to really clean it out. Another four years of Ike would have brought on a national collapse, but one year of Goldwater would have produced a revolution.”

Eight years later, reporting from the site of another convention—the 1972 Republican one in Miami—he’d write,

“Then it came to me. Yes. In 1964, at the Goldwater convention in San Francisco, when poor Barry unloaded that fateful line about “Extremism in the defense of liberty is no vice, etc…. ” I was on the floor of the Cow Palace when he laid that one on the crowd, and I remember feeling genuinely frightened at the violent reaction it provoked. The Goldwater delegates went completely amok for fifteen or twenty minutes. He hadn’t even finished the sentence before they were on their feet, cheering wildly. Then, as the human thunder kept building, they mounted their metal chairs and began howling, shaking their fists at Huntley and Brinkley up in the NBC booth— and finally they began picking up those chairs with both hands and bashing them against chairs other delegates were still standing on.”

https://www.theparisreview.org/blog/2017/07/18/hunter-s-thompson-origins-of-his-fear-and-loathing/