In their first joint campaign event since the Democratic convention, President Joe Biden and Vice President Kamala Harris celebrated Labor Day by addressing a packed Pittsburgh union hall Monday night.

The pair delivered informal remarks as part of the campaign’s Labor Day blitz around the country, making a concerted effort to court union workers ahead of the November election.

As attendees wore shirts with phrases like “Pittsburgh Proud, Union Strong,” Biden and Harris touted their pro-labor record in office and contrasted it with former President Donald Trump’s.

“It’s good to be in the house of labor,” Harris said, heaping praise on Biden for his commitment to protecting unions. “Joe Biden has always stood with the workers of America and labor unions of America. Always, always,” she added.

Speaking before Harris, Biden described his labor record as a joint achievement with Harris.

“Kamala and I are damn proud that we protected the pension of over 1 million workers, retirees,” the president said, speaking also about the job creation numbers under his watch: “60 million new jobs so far, 800,000 manufacturing jobs!”

Biden pledged that the vice president would “build on” his union record if she wins the election.

“Folks, we made a lot of progress, and Kamala and I are going to build on that progress, and she’s going to build on it. I will be on the sidelines, but I will do everything I can to help,” he said.

“And Kamala, believes as I do,” he said, emphasizing their shared beliefs. “Unions are the spine of this economy. She will be a historic pro-union president.”

Earlier Monday, Harris kicked off the Labor Day blitz in Detroit, meeting with union members and delivering brief remarks. Gov. Gretchen Whitmer, Lt. Gov. Garlin Gilchrist, Sen. Debbie Stabenow, Rep. Elissa Slotkin and Rep. Debbie Dingell joined Harris.

“The way we celebrate Labor Day is we know that hard work is good work; we know that when we organize, when we bring everyone together,” Harris said at Detroit’s Northwestern High School gym. “It’s a joyful moment where we are committed to doing the hard work of lifting up America’s families, and I want to thank everyone here for that work and the way you do it every day.”

“So, on Labor Day, and every day, we celebrate the dignity of work,” she later added. “The dignity of work, we celebrate unions because unions helped build America, and unions helped build America’s middle class.”

She also credited union labor with many current workplace standards.

“Everywhere I go, I tell people, look, you may not be a union member, you better thank a union member; for the five-day work week, you better thank a union member; for sick leave, you better thank a union member,” she said. “For paid leave you better thank a union member for vacation time. Because what we know is when union wages go up, everybody’s wages go up.”

Union leaders, including United Autoworkers President Shawn Fain and American Federation of Teachers President Randi Weingarten, stood behind Harris on stage as he delivered her remarks. They took the stage shortly before Harris.

Walz and his wife, Gwen, started off the day meeting with laborers in St. Paul, Minnesota, before attending Laborfest in Milwaukee, Wisconsin. In addition to prominent labor groups, including SEIU, Teamsters, and United Autoworkers, Gov. Tony Evers, Sen. Tammy Baldwin, Rep. Gwen Moore and Mayor Cavalier Johnson were there.

Harris’ husband Doug Emhoff was in Newport News, Virginia, to participate in Rep. Bobby Scott’s annual Labor Day Cookout and deliver remarks, the campaign said.

“Vice President Harris always put workers first and held powerful interests accountable. As California’s attorney general, she fought wage theft to make sure workers got the pay they earned. As senator, she fought tirelessly for the most vulnerable workers, walking the picket line with UAW and McDonald’s workers and introducing a domestic workers’ bill of rights,” the campaign said in a statement.

“Vice President Harris chairs The White House Task Force on Worker Organizing, which made it easier for working people to exercise their right to join a union,” the campaign continued.

“Meanwhile, Trump was one of the most anti-worker and anti-union presidents in history,” the Harris campaign later added, criticizing former President Donald Trump. “He stacked the National Labor Relations Board with anti-labor advocates. He hurt autoworkers, shipped jobs overseas, and lined the pockets of the super wealthy and big corporations at the expense of the middle class.”