PHILADELPHIA.— President Joe Biden, who often says he’s the most pro-union president in history, touted the importance of organized labor and applauded American workers in building the economy during a Labor Day appearance in Philadelphia on Monday.

The Democratic president spoke about how the economy is recovering from the crippling coronavirus pandemic and about what his administration has done to pay for infrastructure improvements, and cited the importance of unions in building the middle class.

As the pace of the Republican primary season escalates, Biden is trying to reclaim ground among working class voters that abandoned Democrats and moved their allegiance to former President Donald Trump and others over cultural issues. And on Monday in Philadelphia he gave a preview of that argument, repeatedly referring to Trump as “the last guy” and likening Trump’s job creation record to that of President Herbert Hoover, who presided over the country as it spiraled into the Great Depression and was soundly defeated by Franklin D. Roosevelt.

Speaking of Trump — who is the leading Republican candidate in the polls so far — Biden said: “He left office with fewer jobs in America than when he got elected into office.»

Biden spoke to a crowd of union members from a diversity of industries — from steel workers to stage hands — and focused on the impact that his administration’s policies have had on working people.

“This Labor Day we’re celebrating jobs, good-paying jobs, jobs you can raise a family on, union jobs,» Biden told the crowd. Instead of standing at the podium, the president held the microphone in his hand and walked around the stage behind signs that read “UNION STRONG.”

Labor Day, a holiday honoring workers, comes this year against the backdrop of increasingly emboldened U.S. unions of all kinds and a potential strike by 146,000 United Auto Workers union members.

The president was asked about whether there might be a strike and said he didn’t think it would happen. That drew a quick reaction from the UAW’s President Shawn Fain, who said he was “shocked” by the president’s words and saying that the president “must know something we don’t know.”

“I think we’ve got a long ways to go,” Fain said. “All three are required to have an agreement done by Sept. 14. That’s the deadline for all three. And if they don’t there will be action.”

The union is pushing for pay raises, a shorter work week and restoration of traditional pensions. Fain said General Motors and Stellantis have yet to put forth a response to the union’s economic proposals, while Ford’s economic offer was far short of union demands. The union has filed unfair labor practice charges against GM and Stellantis for being slow to bargain, charges the companies have denied. Fain said the union’s intent is not to strike but to get a fair agreement.

Labor Day also comes as the U.S. has added jobs and more people have begun looking for work — the most since January. That is news Biden is eager to highlight as he seeks reelection in 2024.

Biden still needs to persuade voters that his policies are having a positive impact on their lives. Only 36% of U.S. adults approve of Biden’s handling of the economy, slightly lower than the 42% who approve of his overall performance, according to an August poll from The Associated Press-NORC Center for Public Affairs Research.

Biden was making his Labor Day speech days after news that America’s employers added 187,000 jobs in August, evidence of a slowing but still-resilient labor market despite the high interest rates the Federal Reserve has imposed.

Friday’s report from the Labor Department also showed that the unemployment rate rose from 3.5% to 3.8%, the highest level since February 2022 though still low by historical standards. But the rate rose for an encouraging reason: 736,000 people began looking for work last month, the most since January, and not all of them found jobs right away. Only people who are actively looking for a job are counted as unemployed.

The president frequently talked about the importance of middle-class workers in the economy, saying that when the middle class does well, “everyone does well.”

At the Tri-State Labor Day event in Philadelphia, hundreds of union workers donning their local T-shirts waited on a warm and muggy morning to see the president speak.

Lenny Nutter, a Philadelphia resident wearing a yellow Laborers International Union shirt, said he attended the event to support Biden, adding that unions have been more active than they used to be, due in part to the president’s policies.

“Unions are adding members, and a lot more work has been given to union workers,” Nutter said.

Biden has used executive actions to promote worker organizing, has personally cheered unionization efforts at corporate giants like Amazon and has authorized federal funding to aid union members’ pensions. Just last week, the Biden administration proposed a new rule that would make 3.6 million more U.S. workers eligible for overtime pay, the most generous such increase in decades.

“Now you’re going to get paid overtime,» the president told the crowd.

Biden also has traveled the country, trumpeting how union labor is building bridges and improving train tunnels as part of the bipartisan $1.1 trillion public works package Congress passed in 2021.

The 36th annual Tri-State Labor Day Parade and Family Celebration is hosted by the Philadelphia AFL-CIO, whose website says it comprises more than 100 local labor unions representing more than 150,000 workers.