Young voter turnout has historically been difficult to count on. But after Vermont Sen. Bernie Sanders connected with the country's youngest voting demographic to help propel his unexpectedly successful primary campaign, it's tough to overlook the youth vote.

Millennials, or the demographic between the ages of 18 and 35, are often discussed as if they're a separate species, with their own unique values, wants and needs that politicians can either cater to or overlook entirely. And typically, the latter strategy hasn't been a terrible one, considering only 38 percent of those between the ages of 18 and 24 years old and 49.5 percent of those between the ages of 25 and 44 years old turned out to vote in 2012, according to the Census Bureau .

That's compared to 63.4 percent of those between 45 and 64 and 69.7 percent of those at least 65 years old who cast their vote that year. Pandering to older voters has been an effective strategy for many campaigns over the years.

But it would be a mistake to overlook the millennial vote entirely, says David Cahn, co-author of "When Millennials Rule: The Reshaping of America," Huffington Post contributor, University of Pennsylvania undergraduate and card-carrying millennial himself. He and his twin brother Jack spent two years traveling the country, talking with millennials and researching their book which breaks down young people's political perspectives and determines what makes this demographic tick.

"I think the story of this election will be the story of voter turnout among millennials," he says. "I think if they turn out and vote for [Democratic nominee Hillary] Clinton, she wins. If they don't, she loses."

But Clinton can't count on the youth vote just because millennials rallied around Sanders in the primaries. Although millennials are often painted as "hippy liberals," Cahn says they have bucked the stereotypes of both parties and largely represent an "unclaimed" generation of voters.

U.S. News recently spoke with Cahn to hear his thoughts about the millennial generation and how it might impact the 2016 election. Excerpts:

Tell me a little about the book. What brought your focus to millennials?

We saw these young people were saying completely different things from the dialogue that's happening in Washington today. They're rejecting Democrats. They're rejecting Republicans. Fifty-percent say they're independent. What's happening?

And in the media, you look at all of the negative stereotypes of millennials. But this is a generation that's really misunderstood and is going to dramatically impact the future of this country.

What's unique about the way millennials think politically? What issues do they care about?

The key difference is what we call 'radical realism.' Millennials are this generation that is rejecting partisanship on both sides of the aisle and is uniting at the political center trying to come up with compromises to a lot of different issues. And the three issues we talk a lot about are the economy, gun control and social issues.

Let's use gun control as an example. Millennials are the most pro-gun generation in America. They're the least likely to support bans on guns, including assault rifles. And that's really surprising to a lot of people, because there's a big stereotype that millennials are hippy liberals and want to take away everyone's guns.

And this was a surprise to me also, but millennials are actually more likely to be in favor of letting people keep their guns. But then you go to gun reform, and millennials are the most pro-reform generation at the same time. Ninety-two percent of them want background checks. They want restrictions on mentally ill individuals from getting guns. They want restrictions on former felons and juvenile delinquents from getting guns.

So slowly this picture started to build for us of this generation that's really thinking critically about these issues and is finding these compromises that they think make sense that are neither Democrat nor Republican.

This was a group that was either just entering the workforce or was preparing to do so when the Great Recession hit. How has that shaped their views of the economy?

I think millennials are suffering to a much greater extent than most people give them credit for. There's a lot of research now around this wage scar. Millennials didn't get jobs in 2008. They didn't get jobs in 2009. And for the next decade, they're going to be earning less money than they could have. Their earning power went down. And when you talk to millennials, that constantly comes up.

I think the response is what makes millennials so different. Sure, everyone's complaining about the economy. What makes millennials different is their response is to say, "We're getting screwed by both sides." Democrats have all this stimulus, and Republicans are going to cut taxes. Millennials don't like either of those solutions. They don't like this traditional basket of political answers to these questions.

A lot of the millennials we talk to say globalization and technological change are rapidly changing our economy. We have to deal with that. The government and our politicians and our leaders should be talking about those issues specifically. We need to be talking about the root causes of this unemployment. We need to talk about the reason there are no jobs instead of throwing these band aid solutions around.

You and your brother have previously indicated millennials don't particularly care for Clinton or GOP nominee Donald Trump. Why aren't these candidates winning over young people?

We saw that the top millennial values according to a lot of different surveys are tolerance and diversity, optimism and authenticity. Hillary Clinton is the least authentic candidate we've seen in a very long time. You can be as liberal as you want, but that's a fact that a lot of people acknowledge. She's one of the least popular politicians, and a lot of millennials are responding and saying, "She's just an insider. She doesn't get it. The system is broken, and it's not working for us. We don't want to vote for her."

And for Donald Trump, they're saying, "He's a racist." Why don't millennials like Trump and Clinton? Well, Clinton's a liar and Trump's a racist. What do you want them to say?

I think millennials are reacting in a very natural way to that, and they want much bigger disruption right now. That's why they voted for Bernie Sanders. They want somebody who's going to change the political system, who's going to have big answers to these big problems instead of fighting over these little issues or the wrong issues. Millennials want big change, and they're not seeing that.

So how do you reach this group? What did Sanders do that mobilized a group of young voters that don't have a great track record when it comes to voter turnout?

You look at [Sanders'] policies, and they don't align all that well with what millennials think about a lot of different issues. But his strength was two-fold. First, he said "I'm an outsider, and I care about income inequality. I'm going to talk about college debt. I'm going to make your issues my issues."

So when Hillary Clinton is going around the country talking about esoteric things millennials aren't as concerned about, and he's saying, "Look, you just graduated from college and have all this debt. I'm going to talk about it," I think that's super effective. Politicians need to start focusing on millennial issues to a greater extent than they currently do. Immigration's important, but millennials aren't making their decision based on immigration. They're making their decision based on the economy and college debt.

The second thing that Bernie Sanders did really effectively is he reached out to millennials and said, "I want you to vote for me." Hillary Clinton went into this election with the explicit intent of not winning millennials.

From the start, Hillary Clinton's strategy was never to win millennials, and you can see that. She's talking to older voters. She won the primary this time. But I think next time, whoever the non-millennial candidate is won't be so lucky. Millennials will be a larger demographic and they'll be better mobilized. So you can't really win anymore by saying, "I'm going to reach out to older voters and be the establishment candidate."

I think the story of this election will be the story of voter turnout among millennials. I think if they turn out and vote for Clinton, she wins. If they don't, she loses. I really think this election boils down to that question, and I think it's a non-trivial question. I spent all these years talking to millennials, researching, writing this book, and I wouldn't put my money on millennials turning out for Clinton. And I think that's a big scare for her campaign, and one she's not taking seriously enough. All Trump needs to win this election is for millennials not to show up.

How do you see millennials changing Washington? Is this a generation that breaks gridlock andmakes bipartisan progress, or are we primed for more of the same?

We're very optimistic about how millennials can change Washington. The fact is, you look at all the surveys, Democrats and Republicans among millennials are very close to each other on the political spectrum. And I think we're going to see the parties align much closer to the center, kind of similar to how Britain works with the Tories and Labour. They're both kind of center-left and center-right parties.

I think what we're seeing now is the implosion of the GOP, which cannot stay relevant and cannot continue to exist as a party with its current platform. That's not over now, and it could take 10 years for the GOP to self-implode and be reborn as a party. And we're seeing Democrats move increasingly closer to the center, especially with candidates like Clinton, and even Obama while he was in office.