There are some obvious economic factors affecting younger voters like heavy student debt and limited job prospects in the aftermath of the 2008 crash that are obvious reasons they would respond to a politician like Bernie who is advocating in an uncompromising language for addressing those issues. Meyerson also sees those and related economic issues as the main explanation for this interesting polling phenomenon:
Finally, the leftward movement of both Democrats and the young, particularly on the central issues of class and power, has been screamingly clear in a succession of polls over the past several years. A Pew Research Center poll in 2011 showed that 49 percent of Americans under 30 had a positive view of socialism—more than how many had a positive view of capitalism. This was at a time when the percentage of young people who could pick Bernie Sanders out of a lineup was surely in the single digits. A New York Times poll last November showed that 56 percent of Democrats held a favorable view of socialism — 69 percent of Sanders’s supporters and 52 percent of Clinton’s. A Des Moines Register poll shortly before the Iowa Caucuses showed that 41 percent of likely caucus-goers actually called themselves socialists.I don't put any great significance on the positive reaction to the word "socialism." As Meyerson notes there, there is no large organization advocating for "socialism" as such in the US.
Such numbers — though they’ve turned up repeatedly — tend to inspire disbelief, or at a minimum, confusion in the pundit class. Most of the normal preconditions for conversions to socialism, or even warming to it, don’t seem to exist in the United States today. There’s certainly no democratic socialist organization out there recruiting large numbers of people. (The Democratic Socialists of America, of which I’m a vice-chair, is a small, barely funded group with minimal presence in most cities, and virtually none outside them.) The labor movement, which is no more (and often less) than tacitly and implicitly socialist, has been shrinking for decades, and has all but vanished from entire regions of the country.
But the meaning of the term has become fluid. With the demise of the Soviet bloc and the replacement of Communism by Islamic terrorism as the national bogeyman, the word "socialism" has lost much of its ability to serve to inspire fear and contempt.
But it's not that the term has fallen into disuse. Along with various other kinds of accusations, Republican media and politicians have routinely accuse our liberal Republican President Barack Obama of being a socialist since he took office. I think there's a "boy who cried 'wolf'" effect going on here. If Obama and his very puzzling attempts to achieve bipartisan harmony with a intransigent and steadily radicalizing Republican Party is "socialism" - which the Republicans have been saying it is - it makes sense that lots of people may find the general concept less scary. As a political insult word, it's a degraded currency.
Meyerson also writes:
I de-emphasize the ideological differences [between the Clinton and Sanders factions of the Democratic Paraty] largely because for quite some time, the line between liberalism (more specifically, what American liberals would want to create if it were politically possible) and actual existing socialism (more specifically, the social democracies of Western Europe) has been growing steadily fuzzier. Socialism no longer means the nationalization of the means of production. It means a vibrant public sector, supported by high and generally progressive taxes, that exists within a market economy to do what the market doesn’t do very well if it does it at all. That is, educate people; provide for their health care; provide resources to retirees, children, and the unemployed; help the poor. It means ensuring that workers have the power to bargain with and, in some places, help shape the priorities of, their employers. It affirms that citizens have economic as well as political rights. [my emphasis]I've discussed issues around state-owned companies here before. Here I'll just note that taking state ownership of some businesses like private prisons would be a very, very good idea. Of the many perverse effects of the privatization demands of the dominant neoliberal economic doctrine, private prisons have to rank among the worst of them.
Kuttner also discusses the student debt issue:
This is the first American generation ever to begin economic life deeply in debt. The entire premise that students should borrow large sums to attend college was horrible policy; it was never debated directly. Republicans are more responsible, because their budget cutting at the federal and state level shifted public financing onto tuition and fees. But both parties have colluded in the basic premise that borrowing to pay for college and starting life saddled with debt is an okay idea.It should also be obvious that student loan debt is not only a serious concern for 20-year-old students and 25-year-old graduates. It a big concern of their parents, as well, who also understand what a serious burden it is for their kids and how it inhibits them in their careers and in forming their own families.
I've been wondering when college students and young adults would finally get into the streets to protest this appalling system. They are at last engaged in protest via the 2016 presidential campaign, and Sanders, who calls for debt-free higher education, is their champion.