Chicago (CNN) The waves of howling applause and standing ovations rolled in at the appointed times, the lines that stirred the faithful in 2016 as potent at the outset of the Trump era as during a grueling Democratic primary contest that saw Sen. Bernie Sanders finish as its defiant runner-up.

This was Saturday night in Chicago, at the People's Summit, and as Sanders addressed loyalists from around the country, rows of diehard supporters, many wearing red, chanted and waved placards with at least one banner declaring an intention to "Draft Bernie."

Asking "what comes next" as it pertains to his 2020 plans is a nonstarter with the Vermont independent. The future, as organizers here are quick to argue, is happening now. Coalition-building on the left, fighting to take hold and remake a party Sanders has pointedly refused to formally join, and strategizing ahead of the 2018 midterms are, truly, the work of the day. Projecting out four years is a stickier wicket, one Sanders has assiduously avoided discussing in any meaningful way.

"It's a little bit early to be talking about 2020," a spokesman told CNN over email. "His focus right now is on defeating Trump's disastrous agenda, to defeat the Republican health care bill that would take health care away from 23 million people and on advancing a progressive agenda to help working families across the country."

Sanders might not enjoy the constant queries, but they are not going away, and not simply because nosy narrative merchants in the mainstream media cannot abide -- or sell readers on -- the nuances of movement politics. Sanders' plans are important, as many activists here readily concede, for reasons they learned the hard way, as his campaign became increasingly hamstrung by the limits of its insurgency. For most here, though, falling short in 2016 was only a first step.

"Absolutely, he should run again," said freshman California Rep. Ro Khanna, who unseated a fellow Democrat, eight-term congressman Mike Honda, last year. "If you look at from the perspective of anyone in the past, if they come that close to the nomination, they'd almost be the de facto nominee the next time. I don't think he should be anointed -- we shouldn't make the mistake of 2016 again -- but absolutely he should run."

Khanna made the political case: Sanders, he said, has the vision, the stamina and "trust at a time when people don't trust anyone in politics" -- but also zeroed in on more pragmatic concerns.

"One of the advantages he would have this time is he'll have an infrastructure, (the support of) more elected officials and the apparatus to be strong," Khanna said.

Among the loyalists at the People's Summit, a three-day convention organized by National Nurses United, the most active and vocal pro-Sanders union, there is broad support for another presidential run. And while most would prefer he again fight for the Democratic Party nomination, others are itching for an independent campaign. The "Draft Bernie" group wants Sanders to break away from the Democrats and form a "People's Party," which he would use to launch either his own 2020 bid or as a platform to lift up another progressive national candidate.

1 of many ways https://t.co/L4oqgyI1gf left mark at #PPLSummit Safe to say attendees, ppl who tuned in, & establishment know about us now :) pic.twitter.com/iYHv51ZdsH — Draft Bernie (@DraftBernie) June 11, 2017

Maria Svart, national director of the Democratic Socialists of America, told CNN the organization would support Sanders if chose to run, but wasn't holding its breath waiting for an announcement. She also spoke about the importance of not leaving the decision until too late.

"He needs to build capacity now and build the ground team," Svart said. "He needs to make a plan, to do what he didn't have time to do last time around, which is absolutely necessary this time around."

Unlike in 2015, when Sanders entered the race and began to draw raucous crowds, and 2016, when his suddenly formidable challenge to Hillary Clinton finally faltered, there is now, in effect, a campaign-in-waiting on the left. Sanders' own "Our Revolution" is a formidable political organization, if for no other reason than its vaunted email list. And an increasingly activated and savvy progressive movement would flock to do the grassroots work most candidates would struggle to match.

Still, Jane Sanders is, like her husband, plainly annoyed by the speculation.

"That's exactly the wrong question," she told CNN's Wolf Blitzer last November, days after Trump defeated Clinton. "Nobody cares (about Sanders' 2020 plans) except the political pundits. He is not -- he's concerned about 2017."

Six months later, the realities of the presidential campaign life cycle are beginning to demand a more nuanced response. Sanders' silence on the matter could eventually put off other potential candidates, allies who might not enter if the godfather of the "Berniecrat" movement was lurking on the sidelines.

"I would say that we intend to play a role in the 2020 election," Sanders told CNN during a brief interview on Saturday, adding with a rare fatalist note: "What that is remains to be decided, but nobody should step back. They should be completely engaged now and the leadership will rise. It will emerge."

Nina Turner, the former Ohio state senator now being pushed by progressive groups there to run for governor next year, was less circumspect.

"I want him to continue to do the work of building a people's movement that is bigger than him," she said, the added with a knowing smile, "And then secondly, yes, I want him to run for president in 2020. Why not?"

Of 2016, Turner said, Sanders simply "needed more time" to match Clinton's organization and reach out to voters.

But there is another clock that might be working against Sanders. Even among devoted supporters here, his age -- Sanders will be 78 when 2020 contests begin -- is a prevailing area of concern.

"I like the idea of him running for president because I think he would do a good job, I just don't think that most of the public will believe that he has the strength and endurance to make it another eight years, let alone four, as president," said Ben Klahn, who organized for Sanders in Michigan.

Klahn recalled a friend telling him recently that she hoped Sanders would "choose someone who really represents him and his ideals and what he stands for and sort of anointing them and having them carry on the movement. To take it from his hands and run with it."

Like who?

"Oh god, I have no idea," he said. "No idea."

Sanders might consider the Democratic Party a mess -- he described its "current model and the current strategy" as an "absolute failure" in a rip-roaring speech Saturday night. But the state of his own movement, though humming along at the grassroots level with a coherence unusual for the left, suffers from at least one very familiar problem: the lack of a bench at the highest echelons.

Were Sanders to stand down, progressives would be met not just with a lack of consensus on who to back in 2020, but few easily named options. Where the liberal center of the party has ambitious elected officials in the mix like Sens. Cory Booker of New Jersey, Kirsten Gillibrand of New York and Kamala Harris of California, to name a few, the progressive field is quieter. Were she to run, Massachusetts Sen. Elizabeth Warren, who has made inroads with the party establishment, has the bona fides to woo the left, but her decision to endorse Clinton over Sanders is still painful for activists who expected her support.

People for Bernie Sanders co-founder Winnie Wong, one of the lead organizers in Chicago, compared the state of play among progressives with the moderate liberal wing of the party, embodied by the Center for American Progress, a Washington think tank run by longtime Clinton ally Neera Tanden.

"CAP has a slate of people that they think maybe will become their candidate," Wong said. "We do not."

"There's a general consensus among all these groups here that there isn't a single candidate that we are uniting behind," she added, "but we would obviously unite behind and organize up behind Bernie."

If they get the chance.