Even in defeat in New York and most likely in the overall quest for the 2016 Democratic nomination, Bernie Sanders has already won in another, perhaps more important way: His brand of politics is the future of the Democratic Party.

Sanders is the overwhelming choice of young voters, scoring 67 percent of voters under 30 in New York even while losing overall amidst a set of election rules that were highly unfavorable to his cause. National Reuters polls now show him with a large 56-38 edge over Clinton with voters below the age of 40.

The votes of old people count just as much, of course, but any young and ambitious Democrat looking at the demographics of the party and the demographics of Sanders supporters has to conclude that his brand of politics is extremely promising for the future. There are racial and demographic gaps between Clinton and Sanders supporters, but the overwhelming reality is that for all groups, the young people are feeling the Bern.

woooo this is fun, is everyone having fun? I am pic.twitter.com/lGCtexmsfK — Matt Bruenig (@MattBruenig) February 8, 2016

Whether the first Sanders-style nominee is Sanders himself or Elizabeth Warren or someone like a Tammy Baldwin or a Keith Ellison doesn't matter. What's clear is that there's robust demand among Democrats — especially the next generation of Democrats — to remake the party along more ideological, more social democratic lines, and party leaders are going to have to answer that demand or get steamrolled.

Young Democrats want a different kind of party

Hillary Clinton's campaign — and, frankly, many DC journalists — has been repeatedly taken by surprise by the potency of some of Sanders's attacks, because they apply to such a broad swath of the party. But this is precisely the point. Sanders and his youthful supporters want the Democrats to be a different kind of party: a more ideological, more left-wing one.

As Clinton put it in the most recent debate, "Under [Sanders's] definition, President Obama is not progressive because he took donations from Wall Street; Vice President Biden is not progressive because he supported Keystone [the pipeline]; Sen. Shaheen is not progressive because she supports the trade pact. Even the late, great Sen. Paul Wellstone would not fit this definition because he voted for DOMA."

To Clinton, Democrats are the party of progressives, and so stuff that Democrats routinely do is, by definition, compatible with being progressive.

But though Democrats are certainly the more left-wing of the two parties — the party of labor unions and environment groups and feminist organizations and the civil rights movement — they're not an ideologically left-wing party in the same way that Republicans are an ideological conservative one. Instead, they behave more like a centrist, interest group brokerage party that seeks to mediate between the claims and concerns of left-wing activists groups and those of important members of the business community — especially industries like finance, Hollywood, and tech that are based in liberal coastal states and whose executives generally espouse a progressive outlook on cultural change.

Sanders's core proposition, separate from the details of the political revolution, is that for progressives to win they need to first organize and dominate an ideologically left-wing political party that is counterpoised to the ideological right-wing Republican Party.

Sanders complicates Democrats' demographic determinism

Sanders's most significant legacy, win or lose, is going to be what his campaign has shown about the ideological proclivities of younger Americans. Specifically, he showed that the hefty liberal tilt of under-35 voters is not a question of Barack Obama's cool-for-a-politician persona or simply an issue of being repulsed by this or that GOP stance.

Clinton tried hard to make waves with superficial appeals to youth culture, include selling Yaaas Hillary T-shirts, appearing with the cast of Broad City, and campaigning in Iowa with Katy Perry.

But the hearts of America's young people — including, crucially, young women — are with the crotchety 74-year-old socialist from Vermont. This both tends to confirm Washington Democrats' conviction that demographic headwinds are at their backs and complicates their hazy sense that faith in demographics is a substitute for political strategy.

The problem is that the young progressives the party is counting on to deliver them to the promised land are, as Sanders has shown, really quite left-wing. They aren't going to be bought off with a stray Snapchat gimmick or two. To retain their loyalty and enthusiasm, party leaders are going to need to change and adapt to what it is these voters want — even at the risk of alienating some of the voters and campaign contributors they already have.

Sanders is succeeding despite many flaws as a candidate

The most striking thing about the traction Sanders has gained in the 2016 campaign is that he really is a badly flawed candidate in any number of ways:

He's old and culturally out of step with his supporters.

He's white, and has spent decades representing a nearly all-white constituency in a party that increasingly relies on nonwhite voters.

His opponent is ideologically out of step with most of her party on foreign policy and national security issues, but he's personally uninterested in talking about these subjects.

He early on failed to gain endorsements from labor unions and other liberal interest groups, even though historically he's been more supportive of their agenda than Clinton has.

He doesn't have the kind of network of think tank and academic wonks who could help him assemble really rigorous policy proposals that would stand up to scrutiny and generate positive media coverage.

His status as a self-professed "socialist" made some sense in the context of Burlington municipal politics decades ago, but it's a general election liability (which becomes a liability for electability-minded primary voters) and relatively little to do with his actual policy stances, which fit comfortably with the left wing of American liberalism.

But though these are all real impediments to him winning the nomination, they are also fairly idiosyncratic â reflecting the fact that he is an idiosyncratic person. And it took an idiosyncratic person to make the decision to run in 2016 at all. But politics, over the long run, is a game for team players and conformists. And team players who look at the success Sanders has had are going to see that they could haveeven more success â not just in presidential primaries, but in primary elections for House and Senate seats and state and local offices â if people who don't have some of Sanders's flaws took his ideas and ran with them.

The small problem of electability

Especially in the context of the 2016 election, there remains the small problem that most experts think Sanders would be a weak general election candidate. Younger Democrats are hungry for a more left-wing, more ideologically rigorous Democratic Party, but after eight years of Obama the general public is not. This is a problem, and one the Sanders campaign hasn't yet offered a particularly compelling or detailed response to.

But the more you think about the long term, the less compelling it seems.

After all, mainstream Democrats have no real plan to win Congressor state offices, so in terms of big schemes for change it's a choice between two different flavors of wishful thinking, not between realism and impracticality.

More fundamentally, the Sanders contention is that if liberals want to change America in fundamental ways, they need to start by creating an ideologically liberal political party. Once you have control of a party, the chance that your Reagan-in-1980 moment may arrive is always lurking out there in the mysterious world of unpredictable events. But if you don't have control of a party, then you are guaranteed to fail.

Sanders may or may not be the right person for the job, and 2016 may or may not be the year it happens. But it looks clear that the rising generation of Democrats want to try to build that party, and that the future belongs to politicians who'll promise to build it with them.

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