He has begun invoking FDR to defend identifying as a socialist, but Roosevelt had no time for these feel-good social and cultural topics. To his credit, Sanders devotes more focus on widening inequality, non-hawkish military policies, and direct election of campaign donors.
And yet if he wants higher wages for working people and narrowing inequality, he should copy his hero and emphasize minimal immigration (supply of labor up, wages down) and a strong labor union movement.
He wants to skip over all the hard work of the early 20th century -- tightening up the borders, deporting foreigners, and building a strong union movement -- and skip right to the prosperous and egalitarian Midcentury. It's no wonder his campaign does best with naive college kids desperate to square the circle of worshiping political correctness while returning to the 1950s.
The last time that populism won big-time, it began under the Republicans, with Teddy Roosevelt pursuing Progressivist reforms -- in the old, political and economic sense, not a frivolous social and cultural sense. Trump will clearly play the role of the latter-day Teddy Roosevelt. But who will follow him to become the next FDR?
It probably wouldn't happen for a few more election cycles, and he would probably be a generation younger than the initiator of populism. So, he would be a Gen X-er (probably a later one, since they're more liberal), and would have begun his political career as a populist insurgent against an entrenched party elite in a major city. FDR started a bit early at the age of 28 as State Senator from New York, but with the lifespan being more stretched out these days, maybe his reincarnation will have gotten his start a little later. Might as well just quote Wikipedia on his political origins:
Taking his seat on January 1, 1911, Roosevelt immediately became the leader of a group of "Insurgents" who opposed the bossism of the Tammany machine dominating the state Democratic Party. The U.S. Senate election, which began with the Democratic caucus on January 16, 1911, was deadlocked by the struggle of the two factions for 74 days, as the new legislator endured what a biographer later described as "the full might of Tammany" behind its choice, William F. Sheehan. (Popular election of US Senators did not occur until after a constitutional amendment.)
On March 31 compromise candidate James A. O'Gorman was elected, giving Roosevelt national exposure and some experience in political tactics and intrigue; one Tammany leader warned that Roosevelt should be eliminated immediately, before he disrupted Democrats as much as his cousin disrupted the Republicans. [Does Trump have any Gen X cousins out there?] Roosevelt soon became a popular figure among New York Democrats, though he had not as yet become an eloquent speaker. News articles and cartoons began depicting "the second coming of a Roosevelt" that sent "cold shivers down the spine of Tammany".
A reminder about Tammany Hall for those who've forgotten their American history class:
After 1854, the [Tammany] Society expanded its political control even further by earning the loyalty of [New York City's] rapidly expanding immigrant community, which functioned as its base of political capital. The business community appreciated its readiness, at moderate cost, to cut through red tape and legislative mazes to facilitate rapid economic growth, The Tammany Hall ward boss or ward heeler – "wards" were the city's smallest political units from 1786 to 1938 – served as the local vote gatherer and provider of patronage.
Insurgent challenges elite of a corrupt party machine whose base is hordes of immigrants -- doesn't exactly ring a bell for any Democrat right now, but then the election where FDR first began to up-end business as usual, in 1910, came one cycle after Teddy Roosevelt had already left his second term in office, paving the way for populism as a winning platform. So the latter-day FDR may not even get his foot in the door until the end of the second Trump administration.
Keep your eyes peeled in 10 years -- an insurgent Democrat just might say, The hell with pandering to immigrant hordes and corrupt party elites, and set himself along the path toward becoming the architect of the New New Deal.