"Jackie,” in which a blood-soaked, chain-smoking Jacqueline Kennedy copes with her husband’s assassination, is the kind of movie that can only be made with the passage of time — 53 years, in this case. If such a wrenching docudrama were attempted when its subject was still alive, depicting her trying to keep her dying husband’s brains in his head, it would have been an act of brutality. Too soon, for her and for the country.

Now, all the adults who witnessed the horrible events of November 1963 are in their 70s or older. “Jackie” represents the last stop on the Kennedys’ long, slow passage into history. Their saga remains fascinating, but it isn’t current anymore — not the back story, not the assassination, and not the Kennedy political brand, either.

From the ’60s to the ’90s — when the Kennedy machine was revved up and waiting for the right moment to take the country by storm — filmmakers felt compelled to have a point of view. The Kennedy-themed movies and miniseries of that era ranged from worshipful (Oliver Stone’s “JFK,” in which Kevin Costner declares, “Don’t forget your dying king”) to veritable oppo-dumps of scheming, profanity, philandering and election-stealing.

“Jackie” is a moving tale about a woman facing an almost impossible situation. It seeks to appeal to the same audience as the new film about Queen Victoria whose trailer preceded it. But it’s almost as much of an echo of a distant past. It doesn’t carry so much as a whiff of a political message, either way. The murdered commander-in-chief could have been a conservative Republican, for all anyone relying on the movie would know.

And that’s got to be a disappointing revelation for Democrats, in their current state of self-reflection, because, though they would never guess it from “Jackie,” the Kennedy brand of politics may be just what they’re looking for.

That brand was created by Robert and Ted Kennedy in the haunted aftermath of their brother’s assassination, drawing on the same public yearning for meaning and connection that Jackie Kennedy tapped into when she compared her husband’s presidency to Camelot.

Only one of those myth-making stories is told in “Jackie.” But the Kennedy political message proved every bit as durable as the Camelot comparison.

It was also, in a large part, an invention. Historians remember John F. Kennedy for his ability to inspire the nation; his shrewd leadership during the Cuban missile crisis; and his relatively conservative handling of a humming economy. He wasn’t a dove, and he was no liberal troubadour, either. On core progressive concerns like civil rights he was on the right side of history, but arguably late to the game. Then, after his death, his brothers Ted, who was always more liberal, and Bobby, who was moving sharply to the left, became the inheritors of his political legacy. And they pushed the Kennedy story in a different direction.

“My brother was the first president of the United States to state publicly that segregation was morally wrong,” Ted declared, in his first major speech in the Senate, promoting the Civil Rights Act of 1964. “His heart and soul are in this bill. If his life and death had a meaning it was that we should not hate but love one another, we should use our powers not to create conditions of oppression that lead to violence, but conditions of freedom that lead to peace.”

Now, virtually all of those people are dead, and the magic that bound them together has dissipated.

Under Bobby’s direction, and then Ted’s, the Kennedy brand combined a sense of bold leadership and vigor, drawing on memories of JFK; a commitment to liberal causes that Bobby, in particular, embodied with his anti-poverty tour of Appalachia in 1968; and an agenda of nuts-and-bolts government programs represented by Ted’s legislative work on civil rights, immigration reform and especially health care.

To conservatives it was all a reflection of boundless ambition, an opportunistic use of the profound sense of sadness and nostalgia stemming from the assassination. But it carried a deeper promise among liberals — the chance to combine the almost messianic desire for social change among young people with an actual governing program.

In the heyday of the Kennedys — as, to some extent, both before and afterward — progressive politicians struggled to unite the movement-driven passions of the left with a set of policies that appealed to union members, farmers and other staples of the New Deal coalition. Lyndon Johnson accomplished much of the difficult, in-the-trenches legislative work that JFK couldn’t, but Johnson soon lost young people and the left over Vietnam. They didn’t really embrace Hubert Humphrey, either. On the other hand, there were purer liberals such as Eugene McCarthy—the Bernie Sanders of his era — who struggled to expand their coalitions beyond cause-oriented young voters; they never seemed like credible-enough candidates to actually serve as president.

The Kennedys, however, may not have been the first Democrats to abandon the Vietnam War — and Bobby himself carried some conservative baggage from the ’50s — but they were the only figures on the left who bridged the gaps between the protesters, the intellectuals and the mainstream. After all, they had actually governed once, and counted a ready-made army of former Kennedy administration officials among their acolytes.

Now, virtually all of those people are dead, and the magic that bound them together has dissipated. (“Jackie,” while a well-reviewed period drama and awards contender, hasn’t exactly attracted a “Rogue One”-style audience.) And yet the Democratic Party is about to realize just how much it misses them.

Ted Kennedy’s last big act on the public stage was his early endorsement of Barack Obama for president. In retrospect, it was a passing of the torch, and Obama did succeed, in a Kennedy-like way, in uniting the Democrats’ desire for both inspiration and mainstream acceptance. Now, Obama is heading into retirement, and the void left by the Kennedys is more apparent than ever.

Once again, the party finds its leaders lacking either movement authenticity or mainstream credibility. Sanders, Keith Ellison and other voices of the left draw suspicion from centrists; those with governing experience like Joe Biden and John Kerry have the same shopworn aura as Hillary Clinton. Those with a claim to blue-collar appeal like Tim Kaine and Sherrod Brown haven’t made big impressions on the national stage, while more charismatic figures like Cory Booker and Julián Castro lack gravitas.

Elizabeth Warren, of course, carries the most Kennedy-like markers; she actually occupies the Senate seat held for 47 years by Ted Kennedy. She also considers herself his rightful heir, having defeated usurper Scott Brown. She inspires liberals with gutsy rhetoric, even if it lacks a Kennedy-like elevation. And, while she hasn’t produced anything like the flood of legislation generated by Ted Kennedy’s Senate office, she has made her mark with some concrete policies, in consumer affairs, banking regulation and student loans.

But Warren still has a ways to go before she can convince America that she’s ready to govern. Among his other attributes, Ted Kennedy was popular among his fellow senators, a regular guy after the TV lights turned off. Warren, the former law professor, is considered more of a divider than a uniter. Could she take some of the edge off her politics to convince her rivals that she’s a decent sort, and in the process reassure moderates? Or is that asking Warren, whose calling card is authenticity, to be someone other than who she is?

Merely asking those questions illustrates just how difficult it is to satisfy all that the Democratic Party demands of a leader — organizer and messiah, governor and crusader. It can take decades to build such an image, and may be easier to inherit it — either by blood or transference, as Obama did and Warren may hope to do — than to create it on your own.

And it’s worth noting that the Kennedys themselves haven’t entirely left the stage, even if the house lights are flickering. John and Jacqueline Kennedy’s grandson, Jack Schlossberg, popped up most recently to author a Washington Post op-ed imploring millennials to go to the polls for Hillary. But he’s 23 and largely unformed. The more immediate family hope is Massachusetts Rep. Joseph Kennedy III — known to some as JK3. Bright, handsome, charming and down to earth, he seemingly embodies all the virtues of his forebears without any of their oft-noticed vices.

But politically, he’s still something of an undergraduate searching for a major. At 36, he seems to be in a state of waiting — for a cause that animates him, for a chance to run for the Senate. Part of his virtue seems to be self-awareness, including the good sense to know that his future isn’t now. But when his moment comes, will anyone remember where he came from?

Peter S. Canellos is editor of “Last Lion: The Fall and Rise of Ted Kennedy.”