Bernie Sanders and Hillary Clinton, who will turn seventy-five and sixty-nine, respectively, by Election Day, have said little about who might lead the Democratic Party in the future. PHOTOGRAPH BY WIN MCNAMEE / GETTY

If you look back several months, you might regret the hours you spent watching the Presidential debates, but then, some might feel that way about binge-watching a series on Netflix: the debates were irresistible. At the same time, one could regret that the inspired idea by someone at Fox News, back in February, to stage a debate_—mano a mano,_ one might say—between Donald Trump and Bernie Sanders was never realized. Both men started out as the unlikeliest candidates of this election cycle, and both, at the very least, will be at the center of things at this summer’s political conventions; Sanders’s impressive Western-state victories on Saturday were reminders of his tenacity and appeal. A Trump-Sanders debate might not have settled much, but it would have been instructive to watch Trump, the developer-capitalist, and Sanders, the Vermont senator and democratic socialist, clarify what they stand for, how they stand apart, and even how they might agree. (For instance, both seem to favor spending the billions used to fight Mideast wars to rebuild the nation’s infrastructure.) But, after both candidates said that they would participate, Trump backed out, citing the old, reliable “scheduling conflicts” excuse.

Had it gone forward, the Trump-Sanders forum might have inspired other variations. With baseball’s interleague play as a sort of model, Hillary Clinton, the Democratic front-runner and former Secretary of State, could debate Texas Senator Ted Cruz, who’s running behind Trump, and the third-place Republican, Ohio Governor John Kasich, could have been available for consolation matchups in subsequent rounds. When viewership dropped off, as it surely would have, voters could once more ask fundamental questions, such as: Who are these people? Who asked them to run for President? Why is it that the United States, which Americans are pleased to call the greatest, or wealthiest, or most liberty-loving country in the history of the world, couldn’t do a little better?

The answers to the first two questions are easy. With the fading of traditional political parties, all of the candidates chose themselves; at the starting gate, at least seventeen Republicans and five Democrats were off and running. Clinton and Trump have been public figures for decades. Candidates with little or no popular support, such as the former, fired Hewlett-Packard C.E.O. Carly Fiorina, and the former Rhode Island governor Lincoln Chafee, having declared their intentions, began to act as if they were serious contenders. Among the Democrats, Sanders and the departed also-rans (Chafee, Martin O’Malley, and Jim Webb) put themselves forward in a year when the Party, which had shaped the politics of twentieth-century America by choosing candidates from Woodrow Wilson to Franklin D. Roosevelt to John F. Kennedy, had come to face a future with no obvious successor generation.

In the past, fresh political talent sometimes arose out of conflict. Sixty years ago, in Chicago, on the eve of the Democratic National Convention, former President Harry Truman sounded a little like former Republican nominee Mitt Romney when Romney attacked Trump: Truman went after the former Illinois governor Adlai E. Stevenson, who in 1952 had run, and lost, to General Dwight D. Eisenhower, and was once more the presumptive nominee. In a handwritten statement, Truman said that his party should nominate “a fighting candidate committed without reservation . . . to the dynamic principles of the party.” Underlining the word “not,” he said that Stevenson was “not that type of candidate . . . he lacks the kind of fighting spirit that we need to win.” Truman didn’t call Stevenson “low-energy,” the phrase that Trump used to unnerve the former Florida governor Jeb Bush, but he did say that Stevenson’s “counsel of moderation seemed in reality a counsel of hesitation.”

Truman insisted that there was nothing personal in his statement—“In fact I like him personally”—although it was in fact fairly personal; by 1956, Truman couldn’t stand Stevenson. He was fairly astute in his assessment of the former governor, who, after winning the nomination, was so hesitant about choosing a running mate that he turned the decision over to the delegates—setting up a floor contest between the Massachusetts Senator John F. Kennedy and the Tennessee Senator Estes Kefauver.* (Truman’s own choice for the nomination, New York Governor Averell Harriman, managed barely fifteen per cent of the vote on the first, and final, ballot.)

Kefauver was the victor, after three ballots, but so, as it turned out, was the party. Although Stevenson went on to lose to Eisenhower for a second time, Democrats were already looking toward the next election, when, no longer having to face the unbeatable Ike, they saw a good chance to take back the White House. A talented political generation had emerged by 1960: Kennedy, who was forty-three that year; the liberal Minnesota Senator Hubert Humphrey, who was forty-nine; the Senate Majority Leader, Lyndon Johnson, who was fifty-two; and Truman’s personal favorite, the Missouri Senator Stuart Symington, a relatively elderly fifty-nine.

Sanders, who turns seventy-five in September, and Clinton, who will be sixty-nine in October, haven’t had much to say about the nation’s future Democratic leaders, perhaps because those leaders haven’t made their presence felt. Trump, who will be seventy in June and carries on with insults and self-inflation (“I alone can solve,” he tweeted after the weekend terrorist attack in Lahore, Pakistan), seems mostly to be accelerating the combustion of the present Republican Party, with not much thought for what might come next. The face of the party’s next generation might belong to the forty-five-year-old Cruz, if not for the complication that, were his Republican colleagues to vote on the matter, he would win a contest for most loathed. Perhaps the most dispiriting thing about this year’s Presidential race, which has sunk to repellent depths because of the Trump-Cruz contest, is the unvoiced promise of more of the same in the years ahead.

*This post previously misidentified the state Kefauver represented.