Liam Clive's voice rings with excitement as he races through the potential for Bernie Sanders's movement to "revolutionize" Congress after the presidential campaign.

"The first step is to really capitalize on the incredible and unexpected momentum and how much the Sanders message has resonated across the country to elect more progressive members to the United States Congress," he says.

Clive is a 16-year-old in Hawaii who says he finished high school last year and worked full-time on Sanders's campaign in the fall. He is also is now a spokesperson for the Brand New Congress, a political action committee founded by former Sanders aides to try fielding a slate of down-ballot candidates who fit the Bernie mold. (The work is unpaid.)

"We can get people who believe in revolutionary change elected to Congress," Clive says. "Bernie has shown the country that it's possible."

Clive's vision is certainly optimistic, but it's not based on nothing. Sanders ran up some massive margins over Hillary Clinton in congressional districts across the country — often in districts whose representatives endorsed Clinton. Given that Sanders won about 40 percent of Democratic primary voters, couldn't some substantial number of democratic socialists get elected to Congress on his basic platform?

Indeed, in this cycle alone, at least 30 congressional candidates are running under Bernie's banner. And the idea that Sanders could unleash a "Tea Party of the left" has generated a lot of media buzz, with his supporters thrilling to the possibility that he could lead a real faction within Congress.

The four political scientists I interviewed for this story all predicted that any momentum for a "Bernie Congress" would dissipate — that the forces Sanders conjured for the primary would scatter without a presidential race to hold them together.

And maybe they're right. But understanding why his down-ballot movement is likely a fantasy may prove just as important for the Democratic Party's future as what's animating the dream in the first place.

Who are the key players trying to bring the "Bernie Congress" to life?

Pinpointing the movement exactly is a bit like trying to hit a moving target. But there are at least key high-profile races to watch where explicitly pro-Sanders candidates have also been endorsed by the Vermont senator, according to Kyle Kondik, of the University of Virginia's Center for Politics:

1) Tim Canova, a law and public finance professor at Nova Southeastern University, challenging Democratic National Committee chair Debbie Wasserman Schultz in the primary for Florida's 23rd Congressional District.

This race, more than any others, is at the top of Sanders supporters' list. Wasserman Schultz has become a key villain in the Democratic primary, scheduling debates that seemed designed for low viewership and openly backing Hillary Clinton. Canova has tightly hugged Sanders, echoing the Vermont senator's call to "join the revolution" on the campaign trail, according to the New York Times.

Canova, a Federal Reserve expert, has raised more than $1 million after getting Bernie's endorsement. But he'll still face steep odds in a district that voted for Clinton over Sanders and for Wasserman Schultz by huge margins since she was first elected to the post in 2006.

2) Zephyr Teachout, a Fordham law professor who beat expectations but lost in a primary challenge against New York Gov. Andrew Cuomo in 2014, is running for an open seat in New York's 19th Congressional District.

Though favored in the Democratic primary, Teachout is the underdog in the Republican-leaning Catskills region of the state, according to the Cook Political Report. Teachout began her career as an academic at Fordham and has written what Sanders recently called "the book" on money in politics, Corruption in America: From Benjamin Franklin's Snuff Box to Citizens United.

3) State Sen. Pramila Jayapal is running for an open seat in Washington's seventh district, which encompasses most of Seattle. The district is one of the most liberal in the country and overwhelmingly supported Sanders in its caucuses in March.

Born in India, Jayapal has become nationally known as an immigrant rights activist, according to a profile in the Seattle Times. Jayapal founded an advocacy organization called OneAmerica to combat anti-immigrant backlash after 9/11.

4) Lucy Flores, a former Nevada State Assembly member, is running in a four-way race for Congress in southern Nevada. The state's kingmaker, Sen. Harry Reid, has endorsed one of her opponents. But her fundraising has taken off since she endorsed Sanders this February, thrusting her back into the spotlight.

And as a Hispanic woman who has been unapologetic about her support for abortion rights, she is the kind of candidate many Sanders supporters say reflects the true diversity of their base.

Then there are another 20 or so long-shot candidates — like a librarian in South Carolina and a Daily Kos blogger in Washington state — who haven't been endorsed by Sanders but are trying knock off incumbent Democrats by recreating his platform. (Howie Klein, a progressive activist, started a fundraising page called the "Bernie Congress" for this group.)

Beyond these insurgents, nine current Democratic members of the House and one US senator, Jeff Merkley of Oregon, have endorsed Sanders.

If all of Sanders's down-ballot allies somehow win, there could be about 30 of them in Congress by next year alone, compared with the 235 Democrats currently in both houses. (Beyond Congress, on Tuesday Sanders directed his donors to support a slate of eight candidates running for various state legislatures across the country.)

The Brand New Congress PAC says 2016 is just the beginning of Sanders's down-ballot movement. On its website, the group declares its intention to field more than 400 candidates by 2017 who "have consistently passed on opportunities to sell out" and "agree completely on a unified economic, social justice, and climate change platform."

The case for "the Bernie Congress"

All of this may sound like a natural extension of the youthful energy surrounding Sanders's campaign. But it's also something of a remarkable novelty: No other losing presidential candidate since at least the 1960s has galvanized his followers for this kind of down-ballot movement, according to Richard Berg Andersson, who tracks presidential primaries for the Green Papers.

"Nobody ran on the Gary Hart/Jesse Jackson bandwagon," Berg Andersson says, alluding to two failed presidential candidates. "I can't think of people looking at any of the candidates Jimmy Carter defeated in 1976 saying, 'I'm going to run on the Frank Church platform.' I can't say this is totally new, but it's something that hasn't happened for at least two generations."

Like Sanders, his down-ballot supporters have largely targeted their opponents for being too close to big business and too wedded to the Democratic Party "establishment," and for being insufficiently committed to key progressive goals, like universal health care and Wall Street regulation.

Alex Law, 25, is running a primary challenge against Donald Norcross, 56, a centrist Democrat in southern New Jersey who has backed the Keystone pipeline and opposed President Obama's Iran deal. (Law would be the youngest member of Congress since Thomas Downey was elected in 1974, according to Fusion.)

"The Democratic Party will respond when we show them we can win victories, when progressive policies can move the needle in terms of winning elections," says Law, who endorsed Sanders early on in his race.

Law tells me the country is growing more liberal, and that the party should reflect that reality by electing a more Sanders-like slate of candidates to Congress.

"I think that's the direction the party is going in, but the speed we get there will be determined by the amount of races that candidates like me, Bernie Sanders, and Tim Canova can win," he says.

Beyond pulling the party to the left, some see taking Sanders's movement down ballot as a way to keep Democrats and young people excited about politics even without the energy of a presidential campaign. (Republicans have crushed Democrats between presidential elections since 2006.)

"Our idea is to run a single unified campaign that looks a lot like Bernie Sanders's," Saikat Chakrabarti, co-founder of Brand New Congress, told Rachel Maddow last week on MSNBC. "We think this is not only a way to galvanize that movement, but to also get voters interested in caring about the midterm elections."

The case against "the Bernie Congress"

But while some see an opportunity for populist challengers to take on centrist Democrats, others see an artificial distinction that misses the party's existing ideological unity.

"If you're talking about a group of progressives pushing a populist agenda, it's already there in the party," says Mo Elleithee, executive director of the Georgetown Institute of Politics and Public Service.

"You can argue about where on the spectrum they lie, but they all talk about raising the minimum wage. They all talk about financial reform. There already is a 'progressive caucus' in Congress."

Of course, there's another potential problem here: that knocking off centrist Democrats with left-wing insurgents will make it more — not less — difficult for the party to advance progressive causes.

In Salon, Sean Illing lavishes praise on the Brand New Congress, saying the Tea Party "succeeded because they systematically altered the Congressional landscape" and that Sanders's aides could do the same. But writing in response at New York magazine, Ed Kilgore makes the convincing case that the Tea Party hasn't exactly helped enact a conservative agenda.

"The Tea Party's excesses cost Republicans control of the Senate in 2012, and produced an environment that's made Donald Trump and Ted Cruz the GOP's only two options for this year's presidential nomination," Kilgore wrote. "Indeed, you can probably thank the tea party for the likelihood of a very good Democratic general election this November."

Why it's so difficult to imagine a slate of left-wing congressional challengers really taking off

But forget for a second whether this is a good idea for the Democrats or not. Is there even a reason to believe it has a chance of getting off the ground?

"It doesn't sound like much of a movement," says UVA's Kondik. "It's a handful of candidates. And it's not clear any of them are going to win. There's not a Sanders army out there in Democratic congressional primaries."

Perhaps the most fundamental reason to believe these left-wing insurgencies won't take off, Kondik notes, is that rank-and-file Democrats just aren't that dissatisfied with the party's leadership.

"If we see that start to change, maybe you see some movement designed to push the party to the left," he says. "But right now Democrats are generally more supportive of their party's leadership than Republicans are."

Compounding the obstacles facing a "Tea Party of the left" is the general lack of existing infrastructure — including think tanks and media outlets — ready to regularly support it, says Matt Grossmann, a political scientist at Michigan State University.

"You have to be in it for the very long haul, with the explicit goal of moving the party to the left or right," Grossmann says. "It's going to take much more than a few congressional candidates supporting Bernie."