Joe Biden and Donald Trump marked the Memorial Day national holiday honoring America’s war dead with jarringly divergent messages that promised to foretell the forthcoming US presidential election campaign as a contest of sharply contrasting characters.

In a ceremony at Arlington National Cemetery, Biden paid tribute to the fallen as heroes who sacrificed themselves in the service of American democracy and ideals. Meanwhile, Trump, taking to his Truth Social site, took a very different tack – bestowing holiday wishes on those he branded “human scum” and accused them of trying to destroy the country.

Biden and Trump are neck and neck in national polling for the 2024 presidential election, with Trump often narrowly ahead. Trump is, however, polling more strongly in the key swing states that will decide the contest.

The targets of Trump’s ire on Memorial Day included the judges who presided over his various trials and a writer who won more than $80m in damages after accusing him of rape.

While his predecessor and 2024 opponent fulminated on social media, Biden – accompanied by Lloyd Austin, the US defense secretary, General CQ Brown, chairman of the joint chiefs of staff, and Vice-President Kamala Harris – visited the the tomb of the unknown soldier at Arlington, final resting place for revered military heroes and US presidents.

Identifying his own family with the notion of national sacrifice, Biden highlighted his son Beau, attributing his death from brain cancer nine years ago this week to his exposure to burn pits while serving in the military in Iraq.

“The hurt is still real, still raw,” Biden said, after describing the “black hole” that opens up for family members who hear the news of the death of a relative serving in wartime.

“I can still hear him saying, ‘it’s my duty dad, it’s my duty. Duty – that was the code my son lived by … the creed the generation of service members have followed into battle on the grounds around us by fallen heroes.”

Biden’s words seemed calculated to contrast with previous comments attributed to Trump about fallen members of the military, whom he is said to have derided as “losers” and “suckers” for allowing themselves to be killed in battle.

If so, the glaring disparity was further emphasised by Trump’s Memorial Day outburst, which reprised previous holiday volleys of abuse aimed at his enemies and opponents.

“Happy Memorial Day to All, including the Human Scum that is working so hard to destroy our Once Great Country, & to the Radical Left, Trump Hating Federal Judge in New York that presided over, get this, TWO separate trials, that awarded a woman, who I never met before (a quick handshake at a celebrity event, 25 years ago, doesn’t count!), 91 MILLION DOLLARS for ‘DEFAMATION,’” he wrote.

That comment was aimed at Lewis Kaplan, the judge in a civil trial brought by the writer E Jean Carroll, who alleged that Trump raped and then defamed her.

“She didn’t know when the so-called event took place – sometime in the 1990s – never filed a police report, didn’t have to produce the dress that she threatened me with (it proved negative)…” Trump continued in reference to Carroll.

He then turned his attention to Judge Arthur Engoron, who ruled in a civil lawsuit last year that the former president and presumptive 2024 Republican nominee had committed fraud by overvaluing his assets – and to Judge Juan Merchan, who is in charge of Trump’s current hush money trial in which he is accused of falsifying documents to cover up an affair with a porn actor.

He referred to Engoron as “the [New York] state wacko judge who fined me 500 Million Dollars (UNDER APPEAL) for DOING NOTHING WRONG” before adding: “Now for Merchan!”

Prosecutors and lawyers are scheduled to present their closing arguments on Tuesday in the trial, which has been running for four weeks and in which Trump faces 34 counts of paying money to an adult film star before the 2016 presidential election, which he won over Hillary Clinton.

The framing of the forthcoming election campaign as a competition about personal character is generally thought to be beneficial to Biden, who is consistently seen to be lagging behind Trump in polls quizzing voters about who has the greatest competence over economic affairs.