BOSTON — Despite all the familiar political-rally trappings — the phalanx of TV news cameras, the anti-Trump words in his remarks and the handheld signs encouraging him to run for president — Joe Biden insisted that the plight of the people picketing behind the stage was more important than the aspirations of the person standing on it.

“I mean, look, I know you’re used to your political speeches, and I’m a politician — I get it. But this is way beyond that,” he said. “This is way beyond that. This is wrong. This is morally wrong what’s going on around this country.”

Biden, the former vice president who is expected to soon join the Democratic race for president, was the featured speaker at a rally for striking workers at the grocery store chain Stop & Shop who walked off the job earlier this month after saying the company’s offer for a new contract would increase health-care costs and slash retirement benefits. The members of the United Food and Commercial Workers union, tens of thousands of which are employed by the chain in New England, have been picketing for more than a week outside the Dorchester-area store where Biden spoke.

Biden, keeping his speech short because of cold rain, cast the dispute as part of a greater devaluation of the American Dream by corporations that prioritize profits over their employees.

“People would bust their neck, people would go out and make their living, people would play by the rules,” he said. “People have done everything they’re supposed to do, and people are entitled to be treated with respect and decency and fairness.

“What’s happening here is workers are not being treated across the board with dignity. They’re not being treated like they matter.”

Biden’s presence was the latest infusion of political star power into the picket line since the three-state strike began April 11.

Last week, Sen. Elizabeth Warren of Massachusetts, another Democratic presidential candidate, stopped by the protest, bringing a box of doughnuts and borrowing a bullhorn to make remarks. On Thursday, more than a dozen local and state politicians spoke at the rally or were mentioned before Biden took the stage, casting themselves as pro-labor.

Presidential aspirants have also tried to win over union voters in other ways. Former San Antonio Mayor Julián Castro said he would support the right of his campaign workers to unionize. Sen. Bernie Sanders (I-Vt.), whose campaign staff was the first to organize, often talks about how he has stood on the picket lines with Marriott workers and supported Disney workers’ attempts to unionize. A frequent warm-up song at Sanders’s rallies is “Union Maid” by Woody Guthrie.

Just before Biden took the stage in Boston on Thursday, about 200 workers marched in a circle at the entrance of the South Bay Stop & Shop shouting, among other things, “Stop & Shop is closed. The Target’s pretty close,” alluding to a nearby competitor.

Workers said they were grateful for Biden’s presence, but they were even happier about the huge crowds and swarm of national media cameras that accompanied him.

“We’re pretty sure he’s using it to his advantage. Everybody sees that. But that doesn’t mean that it can’t also help us,” said Iloisa Brandao, a clerk for Stop & Shop who was handing out small bottles of water to other picketers. “But we’re also using this moment to our advantage.”

As Biden spoke, union members walked through the crowd handing out fliers encouraging people to come to a “mega-picket” on Saturday. They hope the large outpouring of support for workers — and the absence of customers before Easter — will be a gut punch for Stop & Shop, which picketers believe should do more to compensate employees.

“I’m struggling, can’t afford a car, walking to work, living paycheck to paycheck while they’re making these massive profits,” said Nick Barnes, 25, who works for a nearby Stop & Shop’s Peapod grocery delivery service. In the presidential contest, he said, he is leaning toward Andrew Yang, who wants give every American a universal basic income. “I believe Joe Biden is doing it for the voters, but any support we can get is good.

An hour after Biden left, a smaller contingent of Stop & Shop picketers were still marching in a circle outside the grocery store.

Elan Axelbank, who led call-and-response chants, said Biden’s presence was good, but the effort of workers on the picket line matters more. He wished all the candidates who had expressed solidarity with striking workers would do more than make a speech.

“Joe Biden has an email list of hundreds of thousands of people,” he said. “If he really wanted to help, he would send out an email to his supporters, saying not just ‘don’t cross a picket line,’ but telling them to join one.”