“When [Donald] Trump assumed the presidency after a 2016 election that Democrats should have won by a landslide …” writes John Nichols in his new book, “the crisis came into focus. It was not the Republican Party that was ruining our politics. Rather, the lack of a coherent and appealing opposition to the Republicans was the problem.”

You have probably seen versions of this argument hundreds of times. It is the standard left-wing critique of the Democratic Party. The feckless Democrats keep losing because they stand for nothing. Having abandoned their progressive principles and sold out to the corporate Establishment, they have forfeited the trust voters had given them during the glorious New Deal era. Most of these critiques point to the 1970s as the moment when the party turned neoliberal and set itself along the path of political and moral ruin.

But Nichols advances a different argument. In his new book, The Fight for the Soul of the Democratic Party, Nichols, the Nation’s national correspondent, locates the pivotal moment some three decades earlier. The Democrats lost their way in 1944, when they removed vice-president Henry Wallace from the ticket, denying him his place as Franklin Roosevelt’s successor. Wallace, argues Nichols, would have kept alive the New Deal flame that was instead extinguished by the moderate Harry Truman. Instead, Truman’s “great betrayal” (in Wallace’s words, which Nichols endorses) of Roosevelt’s legacy veered the Democrats onto the neoliberal path. “The lost soul of the Democratic Party was a man,” he argues, “and his name was Henry Wallace.”

Nichols has ambitions beyond mere historical reinterpretation. He presents his history as a blueprint for the revival of the Democratic Party’s left wing, concluding with a rousing chapter casting Bernie Sanders and Alexandria Ocasio-Cortez as heirs to the Wallace tradition. His blurbs — from progressives like Sanders, Ro Khannna, Ilhan Omar, and Democratic Socialists of America director Maria Svart, rather than from historians — underscore Nichols’s vision of his protagonist as a redemptive model.