Democratic vice presidential nominee Kamala Harris met the family of a Wisconsin man shot by police last month to kick off her Labor Day visit to a critical swing state, while President Donald Trump assailed the Democratic ticket and tried to put the halting economic recovery under the best light.

Labor Day typically marks the start to the fall campaign season as candidates accelerate their activity for the final sprint to Election Day. But Monday's events are playing out this year against the backdrop of a pandemic that has upended campaigning.

Indeed, this marks Harris' first solo foray out on the campaign trail since she was announced as Joe Biden's running mate nearly a month ago. Biden himself has stepped up his campaigning, traveling to Pittsburgh and Kenosha in the past week.

On Monday. Harris gathered with Jacob Blake's father, two sisters and members of his legal team at the airport in Milwaukee while Blake's mother and attorney Ben Crump joined by phone. Blake joined the conversation by phone from his hospital bed, and Harris told him she was proud of him for how he was working through his pain, his attorneys said. Harris also spoke individually to each member of the family and discussed Biden's police reform agenda, they said.

Biden met with the family last week in Milwaukee before visiting Kenosha.

The meeting kicked off a packed day of Labor Day campaign events, with Harris meeting International Brotherhood of Electrical Workers union members and Black business owners in Milwaukee. Vice President Mike Pence, also sent to Wisconsin, toured an energy facility in La Crosse before delivering a speech that touched on jobs, the economy and protests in Kenosha.

"We will have law and order in every city in this country for every American of every race and creed," Pence said.

At a news conference from the White House, Trump attacked Biden as a leader incapable of handling the coronavirus and reviving the economy, pledging his own "undying loyalty to the American worker." He said Biden and Harris would "destroy this country and would destroy this economy."

Trump briefly mentioned Labor Day and dedicated most of his freewheeling, nearly hourlong remarks to harsh partisan attacks. "Biden is a stupid person, you know that," Trump told assembled reporters. "You're not going to write it, but you know that."

Trump boasted of adding more than 10 million jobs since May without mentioning that's only about half the jobs lost in the pandemic.

Biden, meanwhile, was collecting a trio of endorsements from organized labor as he headed to Harrisburg, Pa., for an AFL-CIO virtual town hall with union President Richard Trumka.

Meeting first with local labor leaders in the backyard of a supporter's home in Lancaster, Pa., Biden spoke about trade, the coronavirus and the economy as he criticized Trump for "refusing to deal with the problems that affect ordinary people" and called for strengthening unions.

The four attendees expressed support for Biden and frustration with Trump's policies. "I can't understand what's going on today, I'm lost," said Bob Faust, a member of the Ironworkers Union. "I get choked up when I think about the direction this country's going in at this time. We need your help."

Trump's narrow win in Wisconsin in 2016 helped to send him to the White House. The state's importance was underscored by all four candidates campaigning there over the past week.

The Biden campaign believes labor support could help get out the vote in states like Wisconsin and Pennsylvania, announcing three union endorsements: the Laborers' International Union of North America, the International Union of Elevator Constructors and the National Federation of Federal Employees, collectively representing hundreds of thousands of union workers.

At the White House, Trump hinted that the U.S. could approve a virus vaccine next month, ahead of the election, as Biden demanded transparency from the government as it studies the shots, along with following the advice of science.

"This could've taken two or three years, and instead it's going to be — going to be done in a very short period of time," Trump said, criticizing Biden for his skepticism that the FDA is operating free of political pressure.

"Could even have it during the month of October," Trump added, calling Biden's doubts "political lies."

Many public health officials and scientists have expressed concerns that the Food and Drug Administration is under White House pressure to approve a vaccine before Trump faces re-election on Nov. 3. Americans may be unwilling to receive a shot if they believe it was rushed to market based on the campaign timetable.

The Associated Press, Bloomberg News and the New York Daily News contributed to this report