The first was 1988, when Michael Dukakis was the establishment choice and Jesse Jackson the insurgent. Al Gore was also in that mix. Some readers may recall that this was the election when then-Mayor Ed Koch said that Jewish supporters of Mr. Jackson “have got to be crazy,” setting a match to the body politic as he was sometimes wont to do.

Mr. Jackson had thumped Mr. Dukakis in Michigan three weeks before. The Massachusetts governor was ahead in the overall race, but matters were up in the air enough that a Times reporter, Michael Oreskes, wrote on the morning of the April 19 New York primary that “even a close second” by Mr. Jackson “might leave the race uncertain and make it unlikely to be settled until after the last primaries, in California and New Jersey on June 7.”

I remember as a young reporter covering a debate between Mr. Jackson, Mr. Gore and the Illinois senator Paul Simon (Mr. Dukakis didn’t show) at Fordham University that March. The only memory I carry of that event was the athletic grace with which Mr. Jackson bounded up onto the stage. But I do recall that in general Mr. Jackson, just like Mr. Sanders now, had the young people and the enthusiasm. Mr. Dukakis was exciting to few.

Nevertheless, on Primary Day, Mr. Dukakis won handily, 50 percent to 37 percent (Mr. Gore, who in one of the less fortunate episodes of his career allied himself with Mr. Koch’s view of things, albeit more discreetly, got 10 percent). The Jackson campaign was over.

Four years later, Jerry Brown was breathing down Bill Clinton’s neck coming into New York’s April 7 contest. Mr. Clinton was ahead, but the Californian, who at the time had fashioned himself a strongly anti-establishment figure, had pulled off a big upset in Connecticut in late March. New York’s most important labor leaders backed him, as did some other progressives.