This combo file photo shows former Vice-President Joe Biden at Texas Southern University in Houston and US President Donald Trump during a meeting in the Oval Office at the White House in Washington, DC. (PHOTO / AFP)

Democratic presidential nominee Joe Biden and US President Donald Trump spent Monday diminishing each other's credentials on the economy and understanding of the "American worker" as the presidential campaign entered its final, post-Labor Day stretch.

While workers live by an "American code", Biden said Trump "lives by a code of lies, greed and selfishness" as he met with labor leaders in Harrisburg, Pennsylvania, a key swing state.

Labor Day typically marks the unofficial start to the fall campaign season as candidates accelerate their activity for the final sprint to election day

Trump, meanwhile, tried to put the halting economic recovery under the best light in a White House news conference where he said Biden and his running mate, Kamala Harris, would "destroy this country and would destroy this economy".

Labor Day typically marks the unofficial start to the fall campaign season as candidates accelerate their activity for the final sprint to election day. Both campaigns reflected that urgency on Monday, as Harris and US Vice-President Mike Pence each campaigned in Wisconsin, a state Trump narrowly won in 2016. The events played out against the background of the coronavirus pandemic, which has upended campaigning and pushed Biden and Harris in particular to conduct much of the traditional election activity online.

While the health of the economy and status of workers were dominant Labor Day themes, both campaigns also focused on recent protests that have roiled Wisconsin and the rest of the nation after police shot Jacob Blake, a black man, in Kenosha last month.

Harris, the first black woman on a major party presidential ticket, met privately with Blake's family at the Milwaukee airport.

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Biden met with Blake's family in Wisconsin last week. Trump did not during a trip of his own last week, instead meeting with law enforcement and business owners whose property had been damaged during protests. Nor did Pence, who touched on the protests during a speech in La Crosse, where he toured an energy facility.

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

Trump painted Biden as a leader incapable of handling the virus and reviving the economy and pledged his own "undying loyalty to the worker"

Out on the trail, signs of the pandemic were evident. While Pence didn't speak with a mask on, workers from the power company he toured did as they stood behind him. Harris was careful not to stray far from blue "X" marks taped on the floor to encourage social distancing as she toured an International Brotherhood of Electrical Workers training facility.

'Undying loyalty'

Earlier that day, Trump painted Biden as a leader incapable of handling the virus and reviving the economy and pledged his own "undying loyalty to the worker".

He boasted of adding more than 10 million jobs since May, without mentioning that's only about half of the jobs lost since the pandemic began. He also said the unemployment rate "plunged" to 8.4 percent. It was a sharper decline than many economists expected from the prior month, but economists broadly view the latest report as evidence that further economic improvement will be sluggish.

And he alleged that Biden and Democrats would "immediately collapse the economy".

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Polls consistently show the economy as an issue at the top of voters' minds.

A strong economy that was Trump's biggest asset for reelection has now become a potential liability, brought down by the coronavirus. Biden said Trump has had an inadequate response to the pandemic, resulting in more loss of life and jobs than necessary.

The US economy has been steadily rebounding from its epic collapse in the spring as many businesses have reopened and rehired some laid-off employees. Yet the recovery is far from complete.

Only about half the 22 million jobs that vanished in the pandemic have been recovered.