MILWAUKEE (NewsNation) — President Joe Biden hit the campaign trail to boost Democrats as crunch time ahead of the midterm elections kicked off, visiting the swing states of Wisconsin and Pennsylvania to mark Labor Day with trade unionists he hopes will turn out in force for his party in November.

Bien first addressed a workers’ gathering at an outdoor park in Milwaukee. Later on Monday, he flew to West Mifflin, outside Pittsburgh — returning to Pennsylvania for the third time in less than a week and just two days after his predecessor, Donald Trump, staged his own rally in the state.

“The middle class built America,” Biden told the gathering in Milwaukee. “Everybody knows that. But unions built the middle class.”

The White House says Biden is celebrating “the dignity of American workers.” The unofficial start of fall, Labor Day also traditionally starts a political busy season where campaigns scramble to excite voters ahead of Election Day on Nov. 8. That’s when control of the House and Senate, as well some of the country’s top governorships, will be decided.

Mary Kay Henry, president of the 2-million-member Service Employees International Union, called Biden championing unions heading into the midterms “critical” and said that the labor movement must “mobilize in battlegrounds across the country to ensure that working people turn out.”

“We’re really excited about the president speaking directly to workers about, if he had the opportunity, he’d join a union,” Henry said. She added: “This president has signaled which side he’s on. And he’s on the side of working people. And that matters hugely.”

Reiterating what he said at Independence Hall on Thursday, Biden in Milwaukee said “MAGA Republicans” are a threat to democracy and have “chosen to go backwards.”

“But together, we can and we must choose a different path forward,” Biden said. “We’re going to choose to build a better America.”

He touted the Bipartisan Infrastructure Law, a $1 trillion bipartisan measure that allocated federal funds for projects in states across America. In Milwaukee, Biden spoke of lead pipe replacements that the bill will help fund.

“Your child shouldn’t have to worry about turning on the faucet … and worry about lead in the water,” Biden said.

Later in Pittsburgh, Biden said America has reached an “inflection point” and must make a decision about its future.

“Things are changing, and the United States has to regain its footing and remember who we are,” he said.

Touting the Inflation Reduction Act, Biden said Democrats were finally able to “beat pharma,” referencing provisions in the bill that allow Medicare to negotiate prescription drug prices.

“No senior, no matter how big their drug bill is … will have to pay more than $2,000 a month,” he said. “If they need insulin, they won’t have to pay more than $35 a month.”

Biden, meanwhile, has a personal history with Pittsburgh’s Labor Day parade, which is among the nation’s largest. He attended the 2015 installment as vice president and returned in 2018. Both times, Biden, now 79, faced questions about whether he’d run for president in upcoming elections — which he opted against in 2016 before winning the White House in 2020.

Vice President Kamala Harris marked Labor Day in Massachusetts, where at a breakfast meeting with the Greater Boston Labor Council, she said, “When union wages go up, everybody’s wages go up.”

“When union workplaces are safer everyone is safer,” Harris said. “When unions are strong, America is strong.”