He, like Trump, breaks the mold and defies the laws of political gravity: He had a heart attack last fall, at the age of 78, and it didn’t scare away voters or slow his stride. While Trump claims leadership of “a movement the likes of which the world has never seen,” Sanders spearheads a “revolution,” to be brought about by “the most unprecedented campaign in the modern history of this country.” And aspects of his pitch — on trade, for example — resonate with the blue-collar workers in the Rust Belt who were important to Trump’s election. While some of Trump’s advisers believe that Sanders would be an easily caricatured foil, others believe that he could be trouble.

Look closely and you see the spirit and lessons of Trump all over the Democratic primary and the Democratic Party. You see it in the Biden campaign’s questioning of the legitimacy of the Iowa results days before The Times discovered and reported on specific irregularities. You see it in Mike Bloomberg’s merciless trolling of Trump with commercials that make him look fat and unhinged, and statements that would be shockingly juvenile but for their mimicry of Trump’s taunts. Julie Wood, a spokeswoman for Bloomberg’s campaign, recently called the president “a pathological liar who lies about everything: his fake hair, his obesity and his spray-on tan.”