Exactly 50 years ago, a senator from Maine stood before the cameras on election eve, and told the American people that the president’s “law and order” campaign was a danger to the country’s freedoms.

The senator was Ed Muskie, and the president was Richard Nixon, and the fight for congressional control in 1970 bears strong resemblance to the choice we will make in November, with Joe Biden taking Muskie’s role, and Donald Trump playing a super-charged Nixon.

The format of the speeches — 15-minute paid commercials on all three major television networks — would be inconceivable today. But the substance of the appeals is similar.

Nixon’s video includes a raucous campaign rally in Phoenix, where he denounced the “black power” protests that had roiled major cities since 1968 — an explicit racial appeal that Trump has mostly avoided.

Muskie appeared against a backdrop at his summer home in Kennebunkport, waves audible in the background, and said the Republican and Democratic campaigns contrasted “the politics of fear and the politics of trust” and that “the leaders of the Republican Party have intentionally made that line a party line.”

The context was a tumultuous year which saw four white students gunned down by Ohio National Guardsmen at Kent State — and, 10 days later, the killing of two black students, and wounding of 12, at Jackson State in Mississippi. The disparity in national attention between the two tragedies was noted then, but resonates more strongly today.

The protests were against the widening of the Vietnam War through the “secret” bombing of Cambodia by Nixon, amid a conflict he claimed to be turning over to the South Vietnamese, rather than the 540,000 American troops Lyndon Johnson had authorized by 1968. In the end, as many American soldiers died on Nixon’s watch as Johnson’s.

Ed Muskie had risen to prominence as a yearned-for moderate voice between the “radical” anti-war protests and the “white backlash” that segregationist George Wallace promoted in the 1968 presidential race won by Nixon.

Muskie’s presidential bid against Nixon later faltered, but that night the politics of reason prevailed over the politics of fear. Nixon hoped the GOP could capture at least the Senate, but gained only two seats and also lost nine House seats.

Five decades later, American cities have again become scenes of mass protest and violent confrontations. Yet the differences are as striking as the similarities.

The “black power” protests that had by then eclipsed the non-violence preached by the martyred Martin Luther King had no coherent objective in the eyes of many, though they featured a strong dose of separatism, a view that white America could never change its racial attitudes.

The coronavirus crisis has, by contrast, revealed enormous disparities that have developed between low-wage workers in “essential” industries — many of them “people of color,” who are disproportionately exposed to COVID-19 — and the elites who govern the country. The current protests have a clear aim: to convince the country these injustices require urgent attention.

Pent-up frustrations that everyone feels from the necessary, hopefully temporary, shutdown of public life were touched off by another appalling incident of what was once called “police brutality.” It was eerily similar to the chokehold death in 2014 of another black man, Eric Garner, in police custody in Staten Island, N.Y. — a case where justice was never done.

George Floyd’s death shows that, despite gains in civil rights since 1970, there is still no justice for many in our criminal justice system, and that racial disparities are at the core of those injustices. The first, tentative steps toward reform in recent years have been nowhere near enough; we must now be far bolder.

Instead, we have a president who calls on police to “dominate” protesters, and dishonors his office by authorizing attacks on peaceful demonstrators to create a “photo op” for himself, using a Bible as a prop in his front of historic St. John’s Church.

The impressions created by this spring’s protests may well set the stage for the electoral decision we ultimately make. A rational fear of the virus is being deliberately stoked by Trump toward an irrational fear of disorder.

Still, the protests of 2020 include hopeful signs. Police officers in Maine cities, and elsewhere, are kneeling and showing solidarity with protesters, something that never happened in Nixon’s day.

And we now have a Black Lives Matter movement. After Kent State and Jackson State, it was clear that the lives of white college students mattered a great deal more than black students.

The outcome in November will tell us a great deal about whether, and how much, we have changed since then.

Douglas Rooks, a Maine editor, reporter, opinion writer and author for 35 years, has published books about George Mitchell, and the Maine Democratic Party. He welcomes comment at: drooks@tds.net