As it happened: Biden's crucial press conference marked by more gaffes

That concludes our live coverage of what was probably one of the more significant press conferences of Joe Biden's political career.

He's determined to stay in the race, and full of warnings about a second Trump administration.

The Democrats seeking to replace Biden don't disagree - that's why they say he should step down.

It remains to be seen how many minds Biden's Q&A changed.

Thanks for joining us. More analysis and in-depth coverage can be found on 9news.com.au.

There were few fireworks in Biden's answers - with the highly anticipated event at times coming across as more of a think tank lecture than an effort to grab voters' attention.

He went into granular detail on geopolitics and rattled off numbers - asking at one moment, though, to not be held to the precise figure.

While it didn't erase the stumbles and blank stares from the debate, it showed that he could engage with reporters' questions on a range of issues without losing focus.

There was still regular coughing and throat clearing. And at times he lowered his voice to a hoarse whisper that evoked the rasp of his voice on debate night.

Overall, his presentation was a reminder that people are focused on him now with an almost clinical eye toward possible slip-ups and mistakes, the kind of pressure that is unlikely to go away for as long as Biden insists he'll stay in the race.

Biden's press conference performance hasn't done much to help fortify the nerves of his colleagues, it seems.

Two more Democrats have issued statements calling on the president to drop out of the race.

California representative Scott Peters and Connecticut congressman Jim Hines added their voices to the row.

Himes said in a social media post-Biden's legacy as a "great president" was secure already.

Peters' statement was published by Politico.

However, the calls to drop out are far from being a majority - and Biden himself pointed out during the press conference that he received largely overwhelming support in the Democratic primaries.

One claim Biden made during his press conference was that internationally, a Democrat victory would be much preferred by US allies.

"How can I say this, without sounding too self-serving? I am not - I have not had any of my European allies come up to me and say 'Joe don't run'," he said.

"What I hear them say is 'You've gotta win, you can't let this guy come forward, it would be a disaster'.

"This guy" would of course be Donald Trump, whose antipathy toward NATO is frank and open - but by Australian political standards, it's a fairly momentous claim to make about a possible national leader who may have to deal with those same European allies in coming years.

Biden also joked that his poll numbers in Israel and "a lot of other places" were better than they were in the US.

Overall, during the press conference, Biden spoke for just under an hour, calling on 11 reporters and answering 19 questions.

A CNN analysis suggested his performance "likely won't change many minds".

Democrats who want Biden to step down are able to jump on a notable verbal gaffe he made at the beginning of the news conference, while Biden's supporters will point toward the time he spent deftly answering a variety of questions on foreign policy.

Toward the beginning of the question-and-answer, Biden mistakenly referred to Vice President Kamala Harris as former President Donald Trump. It was exactly the type of slip-up the White House and Biden's campaign presumably would have feared amid mounting questions surrounding his mental acuity.

"I wouldn't have picked Vice President Trump to be vice president did I think she was not qualified to be president," he said.

The president did not correct himself. He made a similar mistake earlier in the day, accidentally calling Ukraine President Volodymyr Zelensky "President Putin" while introducing him during a NATO event.

But Biden quickly moved on, and he spent the rest of the news conference lobbing in-depth answers about questions including Russia, Israel and his economy, offering deep answers on dealing with China and US policy around Ukraine's fight.

He frequently brushed aside concerns about his candidacy by telling reporters he's the most qualified person to run for president.

"I think I'm the most qualified person to run for president. I beat him once and I will beat him again," Biden said, referring to Trump.

The length of Biden's resume has never been in doubt. The president has had more political experience than any one who has ever held or ran for the office. But what's of concern to those calling for him to step aside is not his qualifications, but his ability to govern for another term.

Fifteen House Democrats have called on Biden to step aside - four of them on Thursday alone. But that still only represents less than 10 per cent of the House Democratic caucus.

Her name came up a lot at Biden's conference - and at one point, should have but didn't - but Kamala Harris has so far not commented on the president's Q&A with the White House press corp.

Instead, the Vice President's X account has posted two messages focused on Donald Trump in the past hour.

"Trump bows to dictators. He makes America weak," Harris said.

"That is disqualifying for someone who wants to be Commander-in-Chief."Another tweet claimed a second Trump administration could restrict reproductive freedom in the US.

Most polls in recent months have showed Biden trailing Trump in key states ahead of their presumed election rematch.

Biden was dismissive of the numbers when asked about them this morning.

"How accurate does anybody think the poles are these days? I can give you a series of polls where we would have likely voters where I win all the time against Trump," he said.

"And in some of them he wins all the time."

He pointed out that the official campaign season hadn't really kicked off yet.

"So, a lot can happen but I think I'm the best - I believe I'm the best qualified to govern and I think I'm the best qualified to win," he said.

"But there are other people who could beat Trump too, but they would have to start from scratch."

Biden offered an eyebrow-raising three-word response when asked about his mix-up of Kamala Harris and Donald Trump's names earlier in his press conference.

A reporter said Trump - three years younger than Biden - was using the incident to mock the president on social media.

"Listen to him," Biden said before he left the stage.