Bernie Sanders can still get a crowd.
At rallies across the country before the midterms, from South Carolina to Michigan to Nevada, people came to see the Brooklyn-timbred senator from Vermont. They rattled the rafters in Wichita, Kan. They screamed his name in Iowa.
Yet as Mr. Sanders ponders another presidential run, what is not clear is whether he can still get the votes.
It is a question that has taken on new relevance as attention turns to the presidential election two years away: While the list of possible Democratic candidates seems to expand every day, political prognosticators have long assumed there would be a Bernie 2.0.
But if Mr. Sanders, 77, was a sensation in 2016, electrifying crowds and awakening fervor on the far left, he is no longer a singular figure among Democrats. Outflanked on the left by rising stars like Alexandria Ocasio-Cortez, Ayanna Pressley and Beto O’Rourke, his stronghold on the party’s progressive wing has weakened. Many of his key policy positions, including Medicare for All and tuition-free public college, have been embraced by others — a victory for him, he would argue, but one that makes his agenda seem less novel.
And while his out-front political presence has kept his name in the mix of 2020 chatter, it has also weakened the anti-establishment appeal he rode to success two years ago.
Mr. Sanders has not made any official announcement that he is running for president. In an interview on MSNBC last weekend, he said he would “make that decision at the appropriate time.”
“I want to make sure that when I make that decision, if I decide to run, that I have concluded in fact that I am the strongest candidate who can defeat Donald Trump,” he told the network.
Mr. Sanders exceeded political expectations in 2016, winning roughly 13 million votes in an essentially two-person race against Hillary Clinton, who got 17 million. He prevailed in 23 primaries and caucuses — compared with 34 for her — including wins in New Hampshire, Michigan and Wisconsin, while struggling in major battlegrounds like Florida, Pennsylvania and New Jersey.
But 2020 would be a far different electoral test for Mr. Sanders. He would likely face far more rivals and far greater scrutiny, which caused him to stumble at times in 2016.
Like other possible 2020 candidates, Mr. Sanders spent the midterms laying groundwork for a possible run.
Before the midterm elections, he campaigned with candidates including Andrew Gillum and Gretchen Whitmer in key battleground states, and crisscrossed the country raising money. He has begun introducing new items to his policy agenda, including proposing legislation to end cash bail. After loudly criticizing Amazon earlier this year over its wages and treatment of workers, he is now attacking Walmart on the same issues — burnishing his credentials as a champion of the working class.
Advisers and people close to the senator speak as if he plans to run, talking privately about his core message and his proven ability to raise money from individual donors.
They also rebuff the notion that his candidacy would not resonate in the same way it did two years ago. In such an unpredictable political climate, Mr. Sanders is at least a known quantity who built a loyal following with his curmudgeonly demeanor and fiery challenge to Wall Street and the Washington elite.
“He’s going to be able to rekindle that spark, partly because I don’t think his spark ever went out,” said Mark Longabaugh, a senior adviser to Mr. Sanders in 2016, who still speaks to the senator regularly. “I think there’s an energized base of supporters that he has out there.”
Early primary polling for 2020, at this point a marker principally of name recognition, suggests Mr. Sanders remains popular, even as he trails Joseph R. Biden Jr., the former vice president. But his numbers have hovered in the teens, which could suggest softening enthusiasm.
One recent poll showed Mr. Sanders in second place among potential Democratic contenders, with 13 percent support, far behind Mr. Biden’s 33 percent, and only slightly ahead of other potential competitors like Senators Kamala Harris of California and Elizabeth Warren of Massachusetts.
“I don’t know if all the folks that loved Bernie Sanders in 2016 are then automatically going to go to him in a 2020 situation,” said Aaron Pickrell, who was a senior adviser on President Barack Obama’s Ohio campaign. This time around, he continued, “a lot of other candidates bring similar dynamics that Sanders has.”
David Kochel, a top Republican strategist in Iowa who has worked on presidential campaigns for Mitt Romney and Jeb Bush, said: “Sanders will fizzle. Lightning doesn’t strike twice for these passion candidates.”
Mr. Sanders declined a request for an interview.
In recent months, aides, advisers and others close to Mr. Sanders have wrestled with how to make old seem new, or at least, newer — and whether that should even be a concern.
Some close to him recognize that the lectern-pounding liberalism that Mr. Sanders embraced in 2016 — punctuated with frequent denunciations of the “millionaihs and billionaihs” — could benefit from a new element or two. Several advisers have suggested he might talk more about foreign policy, including his position that the United States should stop supporting Saudi Arabia in the war in Yemen.
He might also add to his policy arsenal an aggressive call for the government to forgive student loans and concrete proposals for combating climate change, some said.
Others believe that Mr. Sanders has been championing the same policy agenda for decades. Why change anything now?
“I don’t think he needs to add onto the message in the sense that that’s his message,” said Pete D’Alessandro, who was Mr. Sanders’s Iowa campaign director in 2016. “That is his brand.”
There is also a more combustible element to the 2020 campaign: the Trump presidency. Some Democrats have suggested the party should hew closely to a strategy focused on health care and economic issues, but Mr. Sanders appears primed to attack the president, using acerbic language in recent months to denounce him and his policies.
That strategy could appeal to those who want to see their own anger channeled through candidates, yet could backfire with voters in states like Ohio and Wisconsin which flipped to Mr. Trump last time.
One widely reported weakness for Mr. Sanders in 2016 was his struggle for support from black voters, an issue that still divides his supporters. Some strategists acknowledge that he will need to improve his outreach to minorities to have any hope of becoming the nominee, especially during a race that will likely have several minority candidates.
Earlier this month, in discussing Mr. Gillum and Stacey Abrams, two black candidates who lost their elections, Mr. Sanders told The Daily Beast that “there are a lot of white folks out there who are not necessarily racist who felt uncomfortable for the first time in their lives about whether or not they wanted to vote for an African-American.” The comment was not well received.
“It was inartful,” said Nina Turner, the president of Our Revolution, an advocacy organization aligned with Mr. Sanders. “That’s the nicest way I can frame it. What came out of his mouth is not in his heart.”
Ms. Turner, who said Our Revolution would support Mr. Sanders if he runs, said the senator would have to “add race to his class conversations” during a 2020 campaign to appeal more to minority voters.
As other candidates with similarly populist sensibilities also consider runs, including Ms. Warren and Senator Sherrod Brown of Ohio, Mr. Sanders and his allies are confident in his enduring appeal. They point in particular to his 2016 ability to attract young people, a strength that they hope will carry over into 2020. It’s not obvious, however, that it will.
During a swing through Iowa before the midterm elections, Mr. Sanders made a stop at Iowa State University’s homecoming parade, where he was greeted with fervent shouts and cheers. He would later hold a rally for local candidates on campus.
Among those marching in the parade was Jimmie Bragdon, 21, wearing a Democrat-blue sweatshirt. Mr. Bragdon had caucused for Mr. Sanders in 2016, but he said he now thought it was “time for a fresher face in Democratic leadership.” For 2020, he had his eye on Ms. Harris and Senator Kirsten Gillibrand of New York
“In this day and age, people like to see things that are different,” he said later. “Status quo stuff kind of doesn’t stick.”