Nick Salvatore, the biographer of Eugene V. Debs, wrote that the popularity of the great American Socialist leader in the early decades of the 20th century "rested upon his ability to articulate and symbolize something of the severe dislocation experienced by all Americans in the transformation to industrial capitalism."
Bernie Sanders' appeal bears a striking similarity to his political hero's. Debs gave voice to the unease and unhappiness bred by the disruptions of the industrial period. Sanders speaks forcefully for those dismayed by the inequalities and injustices in this era of deindustrialization.
Like Debs, Sanders failed to achieve victory in a presidential contest. Nonetheless, both democratic socialists spoke for many who neither shared their ideology nor voted for them. Just as Debsian socialism had a powerful impact in preparing the way for the New Deal, so will Sanders have an influence on where American politics moves next.
The free-spirited Brooklyn native from Vermont, however, confronts very different political choices than those faced by Debs, who consciously and proudly worked outside the framework of the two-party system. By contrast, Sanders has a long and complicated relationship with the Democratic Party.
Until this election, Sanders ran independently of the party, but he often enjoyed its tacit support. He caucuses with the Democrats in the Senate and exercises a measure of power as a result. He still keeps the party at a critical distance even as he seeks its presidential nomination.
Sanders stands in a tradition of leaders and activists on the American left who, since the days of Franklin Roosevelt, have seen the Democratic Party as a vehicle for egalitarian purposes and have sought to build a strong progressive bloc inside the party.
Now that he has lost to Hillary Clinton, Sanders' task is to maximize his side's influence down the road. Given the threat posed by Donald Trump to so many of his own values, Sanders also has a moral obligation to help Clinton win this election.
So far, Sanders has been effective in influencing the writing of the Democrats' 2016 platform, and Clinton's forces, by past standards in these matters, have been remarkably accommodating to his wishes.
One of Sanders' key voices on the platform committee, Rep. Keith Ellison, D-Minn., supported a draft that took major steps toward Sanders' views. It backed a $15 minimum wage in principle, a more moderate approach to his desire to break up large banks, and a new version of the Glass-Steagall law that had separated commercial from investment banking. The draft would also put the party on record opposing the death penalty.
Sanders did not get everything he wanted. There was no call for a ban on fracking, no endorsement of a Medicare-for-all health care system, no backing for a carbon tax. The drafters also declined to oppose the Trans-Pacific Partnership, but its silence represented deference to President Obama, whose administration negotiated the trade deal.
Still, Ellison praised the document for "significant accomplishments that move our party firmly toward justice, fairness and inclusion." It is certainly one of the most progressive platforms in the party's history.
Sanders, however, is not satisfied. He has yet to endorse Clinton (though he did say he'd vote for her over Trump) and has said he would fight for further platform victories on the Democratic convention floor. He has taken to lecturing Clinton on the steps she needs to take. On CNN's "State of the Union" Sunday, he urged her campaign to "stand up, be bolder."
In the eyes of his staunchest supporters, this is Bernie being Bernie, keeping the pressure on to the very end. But is his fight-to-the-last approach the best way to maximize his leverage on behalf of progressive policies should Clinton defeat Trump?
Sen. Elizabeth Warren, the other leading politician revered by the Democratic left, has made a different choice: She's embracing Clinton fully. Warren campaigned on her behalf this week with enthusiasm, even glee, and seems to have a special gift for getting under Trump's skin.
Clinton, a friend of hers said, has a history of going out of her way on behalf of those who stand with her. Warren has joined this magic circle.
Sanders is staying on its outskirts, maintaining the Debs-style pressure. The risk is that he will lose his moment since some Clinton partisans already see a more centrist campaign as the best way to win over millions of middle-of-the-road voters who find Trump abhorrent. Sanders has to decide if accelerating his plans to endorse Clinton is now the best way to maximize progressive influence.
E.J. Dionne's email address is firstname.lastname@example.org. Twitter: @EJDionne.