A majority of Americans have been telling pollsters for a long time that they consider this nation headed “in the wrong direction” rather than “on the right track.”

Ask Minnesotans of a certain age and political persuasion when they think the nation veered off the track they’d prefer, and they have a ready answer: 1968, and the presidential election defeat of Hubert Humphrey.

A new (and best-yet) Humphrey biography tells me there’s more to that opinion than home-state affection for a favorite son. “Hubert Humphrey: The Conscience of the Country,” by professor emeritus Arnold Offner of Lafayette College, provides a well-researched and readable rendering of a life that bore much good fruit for this country — but could have provided more.

Here at the Star Tribune Editorial Board’s History Desk, we picked up the book and called Offner with an eye to the calendar. Last week was the 50th anniversary of the Democratic National Convention in Chicago, one that those who watched it in real time — even on grainy black-and-white televisions in their parents’ living rooms — won’t forget.

The clubs wielded by Mayor Richard Daley’s police outside the convention as Humphrey won the party’s presidential nomination did more than crack protesters’ heads. They shoved Humphrey into a deep political ditch, down 16 to 18 percentage points in the polls, from which he never fully emerged. And they drove a cultural and political wedge between Americans that in many ways divides this nation still.

Then last week brought another reason to look again at Humphrey and 1968. The outpouring of appreciation for Arizona Sen. John McCain, who died Aug. 25, was not unlike the grief the nation felt when Humphrey died of cancer in January 1978. McCain, too, was a titan of the U.S. Senate whose dream of becoming president went unrealized. McCain, too, spent his last days calling on Americans to overcome their partisan/tribal differences and focus on what unites them.

In 1978, Americans were more interested in praising a fallen hero than in heeding his message. The nation will see in short order whether that has changed.

Esteem for McCain grew in his last years — at least in Democratic eyes — when he vocally objected to the words and deeds of President Donald Trump. Awareness of McCain’s principled role in the Trump resistance makes Offner’s telling of Humphrey’s 1968 campaign discomfiting. His book describes a presidential candidate who deferred too much and too long to a sitting president — Lyndon Johnson — with whom he quietly disagreed on the biggest issue of the day, the Vietnam War.

Humphrey was Johnson’s vice president. Though Humphrey had privately opposed the escalation of American involvement in Vietnam as early as 1965, he felt obliged by his vice presidential role to publicly toe Johnson’s line. But he was also bullied into doing so by a president who — like the Current Occupant — craved power, demanded loyalty and sought to tear down anyone who threatened his primacy.

Standing up to Lyndon Johnson would not have been easy. But by the time Humphrey was on the verge of becoming the Democratic nominee for president, he should have, Offner told me. Humphrey did not, even as protesters of a war he wanted to end were being bloodied by police billy clubs during what Offner’s chapter title calls “the siege of Chicago.”

“He was unable still at that time to face down Lyndon Johnson,” Offner said. “He didn’t act as captain of the team.” Until the second day of the convention, Humphrey was cowed by credible reports that Johnson was plotting with Mayor Daley to swoop into the convention and claim the nomination that he had said on March 31 he would neither seek nor accept.

“Johnson had a powerful grip on that convention. But Humphrey unfortunately underestimated his own standing, his own worth, and the extent to which he could have fought back,” Offner said. He likened Humphrey’s relationship to Johnson to that of an “elder son” in the presence of a commanding father who had spent years grooming him for loyalty. “He found Johnson overwhelming.”

Humphrey did not call for a Vietnam bombing halt that Johnson opposed until Sept. 30. Many players of the ever-popular Minnesota political parlor game “What If” hold that had Humphrey done so at the convention or earlier, he would have defeated Republican Richard Nixon.

Offner doesn’t disagree. Neither does he quarrel with the same what-iffers who blame another Minnesotan, U.S. Sen. Eugene McCarthy, at least in part for Humphrey’s loss. McCarthy’s antiwar campaign for the presidency “broke the hammerlock that Johnson had on the party,” Offner said. For that, he deserves credit.

“But he should have been with Humphrey” after the Democratic convention, Offner said. McCarthy waited until Oct. 29 — one week before the election — to endorse Humphrey. With that delay, McCarthy “deserted not only Humphrey, but all of us, including this author, who looked to him to help the country get out of the Vietnam quagmire.”

But in Offner’s telling, the greater villain is Johnson — the Democratic president who wanted Republican Nixon rather than his own vice president to succeed him because Nixon was more likely to press on in Vietnam. Johnson went so far as to deny Humphrey the evidence American intelligence agencies had gathered of Nixon urging the governments in both Saigon and Hanoi to delay participation in the Paris peace talks until 1969. Without that evidence, Humphrey could not call Nixon to account for arguably treasonous conduct. Americans only learned about Nixon’s meddling in the peace talks in recent years, after Johnson’s White House recordings were declassified.

The lesson for today’s politicians in the new Humphrey biography is the same one they might derive from the accolades for John McCain. Offner put it this way: “You have to act on your principles. You can’t surrender them to expediency. You can’t — even when they tell you that you have to do the politically practical thing. The answer must be no.”

Play the What If game with me: I’d say a Humphrey victory in 1968 would have ended the war in Vietnam in 1969, saving tens of thousands of American and many more Vietnamese lives. It would have discredited the Nixon campaign’s “Southern strategy” of appealing to white voters with racially charged messages about “law and order,” potentially turning the Republican Party in a less racially divisive direction in the 1970s. It would have kept Humphrey’s signature issue — civil rights — high on the national agenda, potentially narrowing some of the race-based socio-economic gaps that persist today.

And it would have spared the nation the Watergate scandal, which contributed much to American cynicism about politics and government.

When politicians don’t stick with their principles, it does more than harm their reputations and their souls. It can set the country on the wrong track for a long time.

Lori Sturdevant is a Star Tribune editorial writer and columnist. She is at lsturdevant@startribune.com.