Senator Bernie Sanders wanted a show of force to convince voters he was back from his heart attack, and he produced one on Saturday: At his first rally since the episode just two and a half weeks ago, he reveled in one of the most coveted endorsements in the Democratic Party, from Representative Alexandria Ocasio-Cortez of New York.
Drawing loud cheers from a large, enthusiastic and diverse crowd that had packed into a park in Queens next to a public housing complex, Ms. Ocasio-Cortez offered resounding words of support, for both Mr. Sanders and his influence in shaping the Democratic primary.
“No one wanted to question the system, and in 2016, he fundamentally changed politics in America,” she said, minutes before Mr. Sanders joined her on the stage. “We right now have one of the best Democratic presidential primary fields in a generation and much of that is thanks to the work that Bernie Sanders has done in his entire life.”
Mr. Sanders declared himself “so delighted” that Ms. Ocasio-Cortez had thrown her support behind his campaign, hailing her as “an inspiration to millions of young people not just here in New York but across this country who now understand the importance of political participation and standing up for justice.”
Mr. Sanders said the crowd exceeded the 20,000 people the campaign had secured a permit for. Campaign officials, keen to affirm Mr. Sanders’s resilience and mindful of the big crowd Senator Elizabeth Warren attracted to her rally last month in Washington Square Park, said more than 25,000 people turned out.
During his remarks, Ms. Sanders also briefly and somewhat indirectly, addressed his health. “I am happy to report to you that I am more than ready, more ready than ever, to carry on with you the epic struggle that we face today,” he said. “I am more than ready to assume the office of president of the United States.”
“To put it bluntly,” he added, “I am back.”
It was a theme that dominated the afternoon, as progressive activists and leaders paraded onto the stage to extend their own words of encouragement.
There was his wife, Jane Sanders, who declared him “healthy” and “more than ready to continue his lifelong struggle to fight for the working people of America.”
There was Michael Moore, the filmmaker, who said he was “glad” Mr. Sanders was 78. “We will benefit from his wisdom.”
And there was Tiffany Cabán, who nearly won the Queens district attorney race earlier this year; Carmen Yulin Cruz, the mayor of San Juan, and Nina Turner, a vocal supporter at his rallies on the campaign trail.
Beyond serving as a show of strength, their presence aligned with a more unifying, inclusive message his campaign is aggressively trying to project.
At the end of his address, he urged audience members to look around and find someone they didn’t know. Then he asked a series of questions designed to promote a sense of unity.
“Are you willing to fight for that person who you don’t even know as much as you’re willing to fight for yourself?” he asked. “Are you willing to fight for young people drowning in student debt even if you are not? Are you willing to fight to ensure that every American has health care as a human right even if you have good health care? Are you willing to fight for frightened immigrant neighbors even if you are native born?”
Last week, the Sanders campaign announced that Representative Ilhan Omar of Minnesota, who along with Ms. Ocasio-Cortez is one of the most prominent left-wing women in Congress, had also endorsed him.
The pair of endorsements, jolted the primary race, signaling that Mr. Sanders was still a formidable contender just as it had increasingly seemed like a contest between Ms. Warren and former Vice President Joseph R. Biden Jr. They also shifted the conversation away from his health issues and his age, infusing his campaign with a renewed sense of vitality.
“There’s been some degree of criticism over all — Bernie Sanders can’t win because his movement is tapped out,” Faiz Shakir, Mr. Sanders’s campaign manager, said. “This discounted that.”
But if the endorsements were an obvious indication that Mr. Sanders was not ready to surrender the party’s left flank to Ms. Warren, it is not clear how much they will ultimately change the race — in part because there are signs that voters are not taking their cues from endorsements.
Ms. Warren, for instance, has attracted huge crowds, posted some of the biggest fund-raising numbers, and surged to the top of national and early-state polls despite lacking endorsements from a single governor, big-city mayor or senator outside her home state. At the same time, Senator Kamala Harris of California is struggling to gain momentum even though she has the backing of politicians across the country, including her state’s governor, Gavin Newsom.
Mr. Sanders’s endorsements could inject fresh energy into a campaign that in some respects needed it badly. Consistently trailing Mr. Biden and Ms. Warren in recent polls and struggling to expand his base, he spent the last two weeks facing a barrage of questions about his health. His campaign made a show of financial strength this month when it reported it had collected $25.3 million between July and September — the most of any candidate in that period — but the announcement was quickly eclipsed by the news of his heart attack.
Mr. Sanders’s aides are also confident that the women will motivate young people, a group that was critical to his success in 2016 and that his allies know he must win over again, both in term of perception and for actual votes.
“I don’t think anyone would question or doubt that they, more than a lot of people, have the ability to inspire young people,” Mr. Shakir said, referring to Ms. Ocasio-Cortez and Ms. Omar. “That in itself is going to be tremendous.”
The endorsements underscore how Mr. Sanders is striving to portray himself as the candidate furthest to the left. In recent months, as support for Ms. Warren has swelled, Mr. Sanders has unveiled policy proposals that have gone beyond hers — including plans to completely eliminate student debt and medical debt, and to impose a wealth tax that would apply to more households and is steeper for rich people than the one Ms. Warren has proposed.
Several Democratic officials and strategists said the endorsements of Ms. Ocasio-Cortez and Ms. Omar — and possibly Representative Rashida Tlaib of Michigan — could stoke enthusiasm among the far left and perhaps prompt some of Ms. Warren’s supporters to take a second look at Mr. Sanders.
But some said the endorsements might not do much to grow his existing coalition, pointing out that the two women carry a similar anti-establishment, populist message that already appeals to Mr. Sanders’s voter base. Some suggested the endorsements could even help Ms. Warren by making her appear more moderate and pragmatic in comparison with Mr. Sanders.
Though Ms. Ocasio-Cortez and Ms. Omar have a big following nationally, and have become preferred targets of President Trump’s, their support may not help woo voters, particularly in critical early states.
Jess Morales Rocketto, a Democratic strategist who worked on Hillary Clinton’s 2016 campaign, said that the endorsements could give Mr. Sanders a fund-raising bump and more news media attention. But she was skeptical that the new support would sway undecided voters.
“I don’t know that a congresswoman from New York, one from Minnesota, one from Michigan are super influential to voters in Iowa, New Hampshire, Nevada and South Carolina,” she said.
Mr. Sanders’s allies said the visual imagery alone — an older man standing with younger women of color — could be enough of a benefit, especially as he continues to fight the perception that his voter base is skewed white and male.
Cori Bush, who was endorsed by Ms. Ocasio-Cortez in her unsuccessful bid for Congress last year in St. Louis, said the endorsements from the two women “knocks away that whole Bernie Bro idea.”
She also said their support “wipes away the idea that maybe he’s not the progressive champion anymore.”
Last month, the Working Families Party, an influential liberal group that backed Mr. Sanders in 2016, endorsed Ms. Warren. The announcement infuriated his supporters. But it also sent a message: It was time for progressives to pick a side and start organizing.
Maurice Mitchell, the Working Families Party’s national director, dismissed the notion that the dueling endorsements would splinter the left.
“We’ve said from the beginning that progressives need to get involved, and that’s exactly what they did,” he said, referring to Ms. Ocasio-Cortez and Ms. Omar. “It’s a good thing for our movement that folks choose one of these candidates.”
Mr. Mitchell said his group — which endorsed Ms. Ocasio-Cortez’s opponent, then-Representative Joseph Crowley, in the 2018 primary — planned to marshal its network of volunteers across the country to work with voters to nominate Ms. Warren.
What is less obvious is the role Ms. Ocasio-Cortez and Ms. Omar will play for the Sanders campaign. Waleed Shahid, the communications director for the progressive group Justice Democrats, which helped propel Ms. Ocasio-Cortez’s congressional campaign, said the two women could mobilize their own networks of volunteers and donors. He pointed to Ms. Ocasio-Cortez’s influence this year in the Democratic primary for district attorney in Queens, where her support for Ms. Cabán helped to nearly lift her to victory.
And because the two congresswomen represent the activist base of the party, he said, they could galvanize progressive activists around the country.
But perhaps above all, the endorsements will help dispel questions about Mr. Sanders’s viability post-heart attack, he said.
Already, there are some indications the strategy could be working.
“I don’t know if it makes him seem less old,” Rashaun Durden, 29, said on Saturday as he waited for Mr. Sanders’s rally to begin. “But I think it shows that the young generation still wants to support him regardless of his age.”