Almost exactly 80 years ago, a Democratic leader from the Bronx huddled privately with President Franklin D. Roosevelt. As told in the powerful new book by historian David Roll, “Ascent to Power, How Truman Emerged from Roosevelt’s Shadow and Remade the World,” Ed Flynn and other leading Democrats were concerned that his vice president, the far Left Henry Wallace, would jeopardize FDR’s bid for an unprecedented fourth term.

Flynn was convinced that keeping Wallace on the ticket would lead to defeat and set out to convince the president to dump Wallace. Had Roosevelt not done so, his replacement Harry Truman would not have become president — and a Soviet apologist would have led the United States.

It’s a precedent which Joe Biden, who fancies himself a new FDR, might want to consider following. The parallels are striking. As with FDR, who would die just months following his reelection, concern about Biden’s health and fitness abound. The 1944 Democratic convention — where Wallace lost his bid to remain on the ticket — was held in Chicago. And Kamala Harris’ poll numbers are even worse than Biden’s. According to the polling site 538’s most recent survey, only 38.2% of those surveyed approved of Harris’ performance.

It is hard to conceive of anything that would better revive Biden’s failing fortunes — and reassure the nation that a capable replacement was waiting in the wings — than the bold act of asking Harris to step aside.

To be sure, the identity politics that led Biden to pick Harris in the first place would be hard for him to confront. But in doing so, he could remind voters of Bill Clinton’s “Sister Souljah” moment — the rapper whom the self-styled Comeback Kid dared to criticize and in doing so established himself as a New Democrat centrist. Not that Harris is as extreme as the Bronx-born rapper — but her word salad speaking style and non-performance when it comes to addressing the migrant crisis, as assigned by the president, have won her no broad public following.

At the same time, Democrats have a deep bench of plausible women to replace Harris. Commerce Secretary Gina Raimondo, a former governor of Rhode Island, private capital investor and Rhodes Scholar, recently got a star turn on “60 Minutes.” She stood up to public sector unions in resolving the pension financing crisis in Little Rhody. Even better, from an electoral perspective, would be Michigan Gov. Gretchen Whitmer, who likes to call herself a pragmatic progressive — and hails from a state whose electoral vote may swing the election. As a Californian, Harris brings no similar boost.

Even more important, both Whitmer and Raimondo have themselves run successfully in closely contested elections and have serious executive experience, something neither Biden nor Barack Obama had before entering the White House. As Biden shuffles slowly off the political stage, such experience would be reassuring to voters — just as was Truman’s experience as the head of a Senate committee investigating World War II contract corruption and his background as a Kansas City county executive.

This is not to endorse Biden — but to suggest that he owes it to the country to look for a vice president convincingly qualified for the most important role of that office: taking over upon the death of the president.

To be sure, Donald Trump, having cut loose Mike Pence — who played a key role in recruiting capable executive talent for their administration — similarly owes it to the country to quickly name his own vice presidential nominee. That person, too, must be able to take over for the 77-year-old Trump, about whose health we can’t be assured either.

Author Roll notes that Roosevelt found a face saving exit for Henry Wallace, as secretary of commerce. Truman, however, distrustful of Wallace for his naïveté about the Soviets, later dismissed him. Wallace, in turn, ran against Truman in 1948 as a Progressive. That election itself reminds us of the present. A four-way race, it featured Truman, Republican New York Gov. Tom Dewey (of Thruway fame), as well as Wallace and “Dixiecrat” Strom Thurmond, who actually carried four Southern states. Truman won anyway.

Face-saving exits for Harris are also possible — whether replacing Merrick Garland as attorney general (the post she held in California) or even Sonia Sotomayor on the Supreme Court,

Dumping Harris would signal that Biden actually has something Americans doubt he possesses: guts. Of course, someone, in an era without big city political bosses, would have to play the role of Bronx leader Flynn. Dr. Jill?