Most of the “Never Trumpers” who opposed Donald Trump’s candidacy in 2016, such as pundits Ben Shapiro, Glenn Beck and Erick Erickson, have now come around to support the president. How can we explain this shift?

We don’t have to wonder. The very same thing happened in 1964, when party loyalty and ideological similarity convinced moderate Republicans to embrace the controversial candidate upending their party. In the late spring that year, as it became increasingly likely that Sen. Barry Goldwater (Ariz.) had a clear path to the Republican nomination for the presidency, twin fears gripped the then-formidable moderate wing of the party: first, that Goldwater might bring catastrophic loss to the Republican Party, and second, that if he were to win, it would bring a dangerous man to the White House.

But rather than going to war against Goldwater, the moderates, led by former president Dwight Eisenhower, first vacillated in their criticism and then relented, ultimately offering active support for their putative enemy.