What explains this shift? It is plausible that European liberals are unconvinced by the foreign policy visions of Democratic hopefuls and detect isolationist tendencies in the party as well. Europeans are still struggling to understand how it was that Barack Obama — probably the most European-minded American president and one most loved by Europeans — was also the one least interested in Europe. (At least until Mr. Trump came along.)

Europeans are also scared by the prospect of a Cold War-style clash between the United States and China. A recent poll by the European Council on Foreign Relations found that in conflicts between the United States and China, a majority of European voters want to remain neutral, finding a middle way between the superpowers. There’s good reason for this: Europe remains economically tied to China in ways that Washington doesn’t seem to appreciate, as evidenced by the recent spat over the Chinese telecom giant Huawei’s plans to build 5G networks across the Continent.

But putting that aside, I believe there is a more fundamental change: European liberals have come to understand that American democracy no longer produces a consensual politics with a predictable foreign policy.