Trump and Harris attend 911 memorial after brutal debate

21st chairman of the Joint Chiefs of Staff Charles Quinton Brown Jr., US Vice President Kamala Harris and US President Joe Biden participate in a wreath laying ceremony on the 23rd anniversary of the September 11 terror attack at the Pentagon in Arlington, Virginia on September 11, 2024. [AFP]

Kamala Harris and Donald Trump shook hands Wednesday at New York's 9/11 memorial to mark the anniversary of the attacks, briefly putting politics aside hours after they clashed in a fiery presidential debate.

The solemn display of unity was a stark contrast to the evening before, when the Democratic vice president forced the rattled Republican former president onto the defensive in a bruising televised encounter.

Any sense of harmony from the commemoration of the 2001 Al-Qaeda attacks is likely to be short-lived, with the US election still on a knife-edge with less than eight weeks to go, despite polls showing a crushing debate win for Harris.

The 78-year-old Trump came out swinging even before the ceremony, claiming -- without evidence -- in an interview with Fox News that the ABC News debate in Philadelphia was "rigged" against him.

"It was a rigged deal, as I assumed it would be, because when you looked at the fact that they were correcting everything and not correcting with her," he complained -- referring to pushback from the moderators to some of his brazenly false statements.

The debate was watched by 67 million Americans, according to final figures from ratings agency Nielsen -- way up from the 51.3 million who watched the catastrophic performance in June that forced President Joe Biden out of the race.

Trump appeared to be in two minds about the Harris campaign's call for a second debate. He initially said on social media "why would I do a rematch?" but later said he'd be ready for two more.

'Stand in solidarity'

The rivals kept their animosity hidden at the Ground Zero memorial, however, in an extraordinary encounter that also included the outgoing president.

Biden, 81, looked on as Harris and Trump shared their second handshake in the space of a few hours -- having had their first-ever such greeting at the start of the debate, in an unexpected move initiated by Harris.

Wearing commemorative blue ribbons, they all then watched as the names of the almost 3,000 victims of the attacks on the Twin Towers were read out.

"We stand in solidarity with their families and loved ones. We also honor the extraordinary heroism on display that fateful day by ordinary Americans helping their fellow Americans," Harris said in a statement.

She and Biden headed later to the site in Pennsylvania where a hijacked plane crashed on 9/11, with Trump following afterwards.

During his visit, Biden briefly donned a red "Trump 2024" cap given to him by a Trump-supporting firefighter. The image went viral but the White House said it was a gesture of "unity."

Biden and Harris later visited the site where another jet was flown into the Pentagon outside Washington in 2001.

'Good job'

The solemn atmosphere could not have been more different to Wednesday night's debate.

Both candidates declared victory but it was former prosecutor Harris who landed blows on issues including abortion and repeatedly managed to bait convicted felon Trump into angry remarks on past grievances.

Trump also boosted a debunked claim about migrants eating pet cats and dogs in Ohio, earning a correction from the ABC moderator.

A CNN snap poll said Harris performed better than Trump by 63 per cent to 37, while a YouGov poll said Harris laid out a clearer plan by 43 to 32 per cent.

US media and commentators broadly agreed Harris had come out on top -- but that it may not move the dial much in a deeply polarized and entrenched electorate.

"I thought Kamala did a good job... and kind of gave us hope," Tanya James, a retired teacher from Texas, said Wednesday outside the White House.

Ikaika Juliano, a musician from Florida, thought however that the Democratic contender "is fake."

Harris meanwhile got a boost with pop megastar Taylor Swift offering her backing minutes after the debate. Trump said Swift would "probably pay a price for it in the marketplace."

But the race remains neck and neck going into the final stretch.

Harris heads Thursday to North Carolina and Trump is due onstage in Arizona, two of the half-dozen swing states expected to decide the election.