Iowa City, Iowa (CNN) On a balcony looking down on Sen. Bernie Sanders' rally here last week, two banners hung side by side: one for the University of Iowa Democrats and another for the Young Democratic Socialists of America, the event's co-hosts.

To the students in the crowd, the juxtaposition was unremarkable. On campus, one University Democrat told CNN, the groups have "a pretty good relationship" and, at least when it comes to social issues, "we definitely overlap with them."

But for the dedicated democratic socialists in the hall -- a handful of whom traveled two hours from Iowa State University in Ames to see Sanders -- the image was a marker of the group's new influence — and increasing mainstream credentials. The Democratic Socialists of America has grown more than tenfold since the 2016 election, when its membership hovered around 5,000. Now its signature red rose hung, literally, over the 2020 Democratic presidential primary.

David Duhalde, the former DSA deputy director who left at the end of 2017 to join Our Revolution, the group spun out of Sanders' 2016 campaign, said events like the one in Iowa City offered a unique opportunity to build a more welcoming electoral coalition.

"It's really exciting to see Sanders speaking to both the College Democrats and a YDSA chapter," Duhalde told CNN. "In order to elect Sanders president we're going to need, borrowing language from the past, kind of a popular front. Both progressive and socialist groups coming together."

Sanders doesn't talk about democratic socialism in his stump speech -- at least not by name. But, during his first week on the trail this year, he made it a point to tick off a laundry list of policies that, when he began his 2016 campaign, "establishment politicians and the mainstream media" had dismissed as "radical and extreme."

"Those ideas that we talked about here in Iowa four years years ago that seemed so radical at that time," Sanders said in Iowa City, as he had at other stops along the way. "Well, today, virtually all of those ideas are supported by a majority of the American people. And they are ideas that Democratic candidates from school board to presidential candidates are running on today."

The "S-word" label

The Democratic Party has moved left in the wake of Sanders' 2016 success, too far for some in its moderate wing's comfort, creating another juicy juxtaposition: When DSA endorses Sanders, as expected, in the coming weeks, it will throw its grassroots support to a top candidate for the Democratic Party's presidential nomination -- something unthinkable, from both sides, a few years ago.

How the group's activist intensity will be welcomed by Democrats who fear the "S-word" label remains to be seen. Skeptics within the party point to the midterms, when Democrats won their House majority by flipping seats in purple congressional districts, as a reason to pump the brakes. But presidential races play out on different terms, and the 2020 sands are constantly shifting.

President Donald Trump and his campaign have already begun efforts to set the narrative, sending out almost daily email and text message warnings about the specter of "full-blown socialism." And at the President's State of the Union address last month, Trump said he was "alarmed by the new calls to adopt socialism in our country" and pledged that "that America will never be a socialist country."

As Trump offered his resolution, Republicans and some Democrats rose to applaud. Naturally, the cameras turned to Sanders, who sat impassively, his index finger drawn across his chin. He was a couple weeks from entering the Democratic primary and surely knew his reaction would be the subject of scrutiny.

Duhalde connected the scene in Iowa City to Sanders' reaction that night on Capitol Hill.

"I think Sanders understands that he is representing a historic legacy, that he has been part of a larger movement that shaped him, and that he needs to own who he is," Duhalde said. Less heartening, he noted, was the smattering of cheers for Trump's declaration from the Democratic side of the aisle.

The ideological divide among Democrats in Washington -- often headlined now by another democratic socialist, New York Rep. Alexandria Ocasio-Cortez -- is less pronounced on the campaign trail. The early announced leaders all come from the party's growing progressive wing, and their differences can often appear more tactical than ideological.

The warnings from centrist hopefuls, like former Colorado Gov. John Hickenlooper, that the party risks losing moderate voters in its pursuit of progressive primary-goers have mostly been ignored. A bid from former Vice President Joe Biden could sharpen the debate, but for now, most of the candidates have limited their pushback to politely informing reporters they are not, in fact, democratic socialists themselves.

Among Democratic rally-goers in Iowa last week, questions about "socialism" were greeted on a spectrum of shrug-to-hug. At the Iowa Memorial Union, the embrace was warm, if occasionally muddled.

Olivia Stecklein, 19, drove 90 minutes from Dubuque, Iowa, with two friends to see Sanders -- for a fourth time, after attending his events in 2015 and 2016, before she could vote.

"I don't think I can define what I am right now," Stecklein said, when asked whether she identified as a democratic socialist. "I just definitely support most of Bernie's issues. From what I know, I wouldn't care about giving up more of my paycheck if it meant more for others. That's what I get from 'socialism.' I don't view it in a negative way."

"Anti-capitalism" gains traction

For some progressives, especially on college campuses, there is no sense of contradiction in staking out positions with both the Democratic Party and democratic socialists. One of the speakers that introduced Sanders in Iowa City, junior undergrad Austin Wu, is a member of both the University Democrats and YDSA. He is also in student government, currently serving as its deputy city liaison. Wu was the point of contact between YDSA and the campaign, which asked him to address the crowd, he told CNN.

"(Sanders) has been the catalyst for a new wave of progressive candidates, ideas and policies that seek to reverse this new 'gilded age' that has denied millions of Americans the better life they deserve," Wu said Friday night, channeling the candidate who would follow him onstage a few minutes later.

Like Wu, Iowa State's Ashton Ayers has roles with both the YDSA and the campus Democrats. He first heard Sanders speak nearly five years ago in a church basement in Des Moines. The experience was a revelation, he told CNN, and set him off "looking into all sorts of different politics and from social media I learned about the Democratic Socialists of America and got involved because that message really spoke to me."

Now, Ayers speaks to other students looking for a political home outside the traditional mainstream. That includes those like him, from "pretty dang conservative" backgrounds in southeastern Iowa.

"If I'm going to use an economic framework, I always say 'anti-capitalist,'" Ayers said. "The DSA is a big tent leftist organization. I think it's a big tent anti-capitalist organization. The system of capitalism is predatory and it creates an inequality, racial inequality, environmental inequality, social inequality, sexual inequality. So that's how I always present it, as anti-capitalist."

Polling suggest that could be a potent talking point, especially with younger voters. A 2018 Gallup poll found that only 45% of Americans between the ages of 18 and 29 have a positive view of capitalism. That number is down from 68% in 2010. Capitalism rules most consistently with older Americans, with their support actually trending up to 60% in 2018, over the last decade.

Positive views of socialism have remained pretty much constant, across age groups, during the same period, during the same period -- its popularity decreasing as the population ages.

Sanders' surprise 2016 surge and the ascendance of Ocasio-Cortez, along with the growing purchase of their ideas within the Democratic Party, have bulldozed a path for groups like DSA to play a more meaningful role on the campaign trail. They have backed down-ballot winners everywhere from the Virginia to Pennsylvania and Chicago -- successes that have made it easier to recruit and attract activists less inclined to engage in party politics.

"In Sanders' last presidential campaign, he opened the window of opportunity and I don't think that window can be closed again," DSA national director Maria Svart told CNN. "But it's very important that we use this opportunity to build a movement that will last beyond the election. That's the way we view this -- as a fight for our future, a fight for the planet. A fight that doesn't end in November of 2020."

Trump's attacks against socialism, Svart said, confirmed what the expanding ranks of DSA's dues-paying membership had suggested: the group's influence is rising and its positions increasingly accepted in the broader political discourse. Opponents are worried. Asked if she was concerned that Trump and the Republicans could successfully scare off voters with visions of Venezuelan turmoil, Svart demurred.

"Let's not forget that Trump also called Obama a socialist. Obama was clearly not a socialist," she said. "So this idea that somehow, uniquely, this is a smear that can only be used against us and Bernie is definitely not true."