The Republican foreign-policy experts explain in their ‘Open Letter on Donald Trump‘: “We have disagreed with one another on many issues, including the Iraq war and intervention in Syria. But we are united in our opposition to a Donald Trump presidency.”

They are right to unite. Their peroration is equally right:

Mr. Trump’s own statements lead us to conclude that as president, he would use the authority of his office to act in ways that make America less safe, and which would diminish our standing in the world. Furthermore, his expansive view of how presidential power should be wielded against his detractors poses a distinct threat to civil liberty in the United States.

Only this is understated. Someone who has achieved the stature of a leading candidate has already acquired a degree of power, which is sufficient to make the world hang on every word. On Wednesday, the national-security journalist Benjamin Wittes wrote: “Trump has done more than any single person to undo two presidents’ earnest and consistent protestations that the United States is not at war with Islam.” This is already the reality. The national-security misfortune—this is taking place daily. “Our standing in the world,” as the letter says— this could be charted with a downward-plunging graph.

I see that all kinds of people respond to the Republicans’ letter by dryly noting that Trump’s potential electorate is not going to care. But this is not true. The Trump campaign has reached the point where the electorate in question has expanded upward to the elite. It is daunting to consider that Gov. Chris Christie, unlike Trump, has made serious efforts to learn about the world, and, even so, felt not a moment’s hesitation—not a single doubt as to his own dignity—in rushing to Trump’s side. Such is the lure of ambition.

Or maybe something darker is taking place, and maybe an ideological tone is clarifying around Trump’s candidacy, and Republicans with fundamentally authoritarian instincts are beginning to shoot glances at one another and to see their opportunity. The letter from the Republican foreign-policy experts is addressed to those people, the politicians, wonks, and journalists alike—the ones who right now are trying to decide if Christie isn’t smarter than the rest of them.

Vast, vast are these developments—the crumbling of the traditional Republican Party, the rise perhaps of a dreadful populism, the potential for enormous shifts of opinion and affiliation to the Democratic Party.

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