President Donald Trump was following up his all-out assault on Joe Biden at the Republican convention with a rally in New Hampshire on Friday, as the Democratic challenger plotted his own return to the live campaign trail after months under coronavirus lockdown.

Fresh from the hyperbolic claim during that "no one will be safe in Biden's America," Trump was to hammer that "law and order" theme again in the city of Manchester.

New Hampshire is a state he only narrowly lost in 2016 and now thinks he can add to the win column in what will likely be a tight contest in the electoral college on November 3.

For weeks, polls have shown Biden with a solid lead around the country, including in swing states, while Trump has been uncharacteristically fumbling in attempts to land blows on the centrist Democrat.

But growing racial tension and violent protests against the police have given the Republican a new focus, which he delivered in lurid terms at the close of the Republican convention in front of the White House late Thursday.

Turning narratives -- and in many cases facts -- on their heads, he brazenly cast Biden as a pawn of the extreme left, a promoter of anarchy, and all but anti-American.

"This election will decide whether we save the American Dream," Trump said. "He'll be the destroyer of American greatness."

Violence in Wisconsin

Trump goes into the election carrying a staggering amount of baggage for an incumbent.

He is only the third US president to have been impeached. A string of close associates have been charged or jailed.

He has been dogged throughout his first term by allegations of racism and corruption. And polls show about two thirds of Americans say his management of the Covid-19 pandemic -- which has killed more than 180,000 Americans and put millions out of work -- is a failure.

But a summer of racial unrest and frightening footage of rioting and looting has thrown the president a lifeline, as he stirs up his white, working class base, while trying to lure worried independents over to his side.

Violence this week in Kenosha, Wisconsin, where police shot an African-American man in front of his children during an attempted arrest, has brought matters to fever pitch.

"If the left gains power, they will demolish the suburbs," Trump said in yet another wildly exaggerated line from the stage in front of the White House's South Portico -- the first time a president has broken with etiquette to host a party convention at the so-called "people's house."

The audacious Trump "law and order" strategy puts Biden in a bind.

His most active base includes African Americans and leftists, so he needs to support their condemnations of police violence and calls for reform.

At the same time, to win he will need to claim the middle ground that Trump is trying to tap into -- and that means condemning rioting and persuading independent voters that he will not rule too far from the left.

Until now, Biden largely campaigned online from home. What began as a decision to adhere to coronavirus safety measures turned into a broader plan to keep a low profile while Trump committed frequent unforced errors.

But with the president stepping up a gear, Biden is finally "coming out of the basement," as his opponents mockingly say.

Biden announced Thursday that he'd soon be hitting the trail, with a focus on the swing states where the election will ultimately be decided, including Minnesota, Pennsylvania, Arizona and Wisconsin.