Donald Trump’s candidacy has been met with alarm, if not utter scorn, by many leading neoconservative intellectuals, with several threatening to bolt the Republican party in favor of Hillary Clinton if he becomes the party’s presidential nominee.

This noteworthy development, which has great significance for the Republican race and the future of the party, has special interest and meaning for me because I devoted a chapter of my doctoral dissertation to the rise of the neoconservative movement, dating back to the late 1960s and early 1970s, if not earlier, and coming out of the New York Jewish intellectual milieu. Among that illustrious crowd’s distinguished figures, Irving Kristol and Norman Podhoretz — then editors of the Public Interest and Commentary, respectively — are regarded as the leaders of this influential intellectual movement. Others closely associated with the movement at the time were Nathan Glazer, Gertrude Himmelfarb, Hilton Kramer, Midge Decter, Joseph Epstein and Walter Laqueur, among others.

This diverse group of prominent intellectuals did not always write on the same subjects and, even when they did, the emphasis and tone was not always the same. Indeed, there were inevitable subtle and nuanced (and, at times, not so subtle and nuanced) differences between them. But when they burst onto the intellectual and political scene in the 1970s and 1980s as a more or less coherent movement, the neoconservatives all shared a common worldview.

Salient components of their thinking not only included a commitment to and defense of Western values, traditions and institutions; a muscular foreign and defense policy; and a modest social safety net. They also strongly believed, as one of the major lessons of the Holocaust, of the need to ensure the security and survival of Israel, as well as to defend Jewish interests at home and abroad. Taken together, the neoconservatives saw — and still see — the United States, while not perfect, as a positive force for good in the world. As such, they celebrated the country’s bourgeois values and became vocal enthusiasts for the notion of American exceptualism.

Several developments that took place in the 1960s helped fuel the rise of the neoconservative movement, including the following: the Soviet’s aggression around the globe; the growing prestige and status that intellectuals came to enjoy in the United States; the resurgence of ethnicity; the 1967 Israeli war, when the Jewish state’s survival hung in the balance, with Jews fearing another Holocaust; and the breakdown in the black-Jewish coalition.

In response, beginning in the late 1960s, the neoconservatives vainly tried, from within, to save the soul of the Democratic party, which they believed was becoming captured by the left. But after the party continued to move further leftward during the 1972 McGovern campaign and in the years afterward (manifested, in their view, by its resistance to confronting the Soviet Union and by its growing hostility toward Israel), they broke ranks, casting their lot with the Republican party, where they thought both American and Jewish interests would be better served. Later, from positions both within and outside of government, the neoconservatives became influential players on foreign and defense policy in the first Reagan administration, when they pushed for a tougher stand against the former Soviet Union to counter the threat of Communist totalitarianism, which they saw as the greatest moral and political challenge of the time.

Since then, a younger generation of neoconservative intellectuals has continued to fly the neoconservative’s banner. Following in their fathers’ footsteps, William Kristol and John Podhoretz, from their perches as editors of The Weekly Standard and Commentary, respectively, have helped spearhead the more recent and current neoconservative fight. Some members of the younger generation include Paul Wolfowitz, Elliott Abrams, Douglas Feith, Robert Kagan, Max Boot and James Kirchick.

What unites the older and younger generation of neoconservatives is a similar political and cultural outlook. Like the older generation, the younger generation favors an interventionist foreign and defense policy, and upholds highbrow culture against what they see as a lowering of artistic and aesthetic standards. Like the older generation, they also strongly support Israel and Jewish interests. And like the older generation, the younger generation has fully embraced the Republican party, where they, along with some of their elders, visibly played a significant role in George W. Bush’s administration as forceful proponents of the Iraq war, which they viewed as a first step toward promoting democracy and transforming the Middle East.

Now, however, that erstwhile alliance seems to be coming apart in light of Donald Trump’s campaign, with many neoconservatives deeply troubled by his temperament and his simplistic, if not unconventional and emotionally charged, views. Indeed, one of the things that the neoconservatives find appalling is Trump’s highly inflammatory, racist and xenophobic rhetoric. In a widely publicized op-ed piece in the Washington Post, Robert Kagan bluntly wrote: “…Trump [has]…tapp[ed] [the] well primed gusher of popular anger, xenophobic and, yes, bigotry, the [Republican] party had already unleashed.”

The neoconservatives also see Trump’s lack of knowledge on foreign and national security issues, as well as his apparent isolationist leanings, posing a significant danger to America’s image and interests around the world. Emphasizing this point, Max Boot, in a hard-hitting interview in Vox, recently said: “Donald Trump would destroy American foreign policy and the international system as it’s been built up since World War II…[He] does not have a serious foreign policy thought in his head…His impulses are derived from the same well that people like the America First Committee and Joe McCarthy tapped into, which is essentially a form of isolationism…”

What’s more, neoconservatives see Trump’s narcissism and apparent lack of any core values and beliefs as the perfect embodiment of postmodern decadence. As John Podhoretz acerbically remarked in a recent issue of Commentary: “Donald Trump [is] the ultimate postmodern man…He is interested in the Donald Trump narrative and nothing else…His claims don’t have a sell-by date; they have a sell-by time. They expire at will the second after they emerge from his mouth.”

No less troubling, from a Jewish perspective, neoconservatives see Trump posing a potential threat to the future of Jewish life in America, where Jews have hitherto enjoyed unprecedented freedom and acceptability. In a bracing article in the Tablet magazine, James Kirchick, astutely observed: “A country that is politically pluralistic, open to new ideas and new people, ethnically diverse, and respectful of religious difference, is a country that will naturally be safer for Jews than a country that is none of these things. This, I believe, is why so many Jews, foreign policy hawks or not, innately fear Donald Trump… If there’s a silver lining to the resistible rise of Donald Trump, it’s that it has forced us to realize this truth.”

In light of these concerns, Kagan and Boot have already declared (and Kirchick has done so implicitly) that they would vote for Hillary Clinton. What other neoconservatives decide to do remains to be seen. But it is not hard to imagine, as the election process unfolds, more moving into Clinton’s corner. If this were to happen, some of the neoconservatives would ironically find themselves coming home again to the Democratic party.

In the meantime, despite Trump’s defeat in Wisconsin, he still could be the GOP’s presidential nominee, given his potential strength in the remaining primaries, particularly those in the Northeast, as well as his ability to woo the number of unbound delegates. Granted, it is more challenging now, but it is still possible he could be the nominee. While not a neoconservative myself, I agree that if, indeed, Trump emerges from the Republican convention in July at the top of the ticket, there is a moral imperative for anyone who truly cares about the future of America, as well as the Jewish community and Israel, to do everything in their power to prevent him from being elected.