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.

Biden's fired up as he spoke about what drove him to stay in the running, saying he has to "finish the job".

"More children are killed by a bullet than any other cause of death! The United States of America! What the hell are we doing? What are we doing?" he said, raising his voice.

"We've got a candidate saying don't worry, I'm not going to do anything, I'm not going to do anything.

"We've got a Supreme Court that is what you might call the most conservative court in American history. This is ridiculous. There's so much we can do still. I'm determined to get it done. It's about freedom."He suggested democracy was "under siege"."

But the other reason why I didn't want to hand off to another generation, I have to finish this job," he said.

"I've got to finish this job because there's so much at stake".

Biden's going to be hitting the road to "allay fears" about his competence, he said.

"For the longest time, it was, you know, Biden is not prepared to sit with us unscripted, Biden is not prepared ... anyway," he said.

"What I'm doing is what I have been doing, we've done over 20 major events from Wisconsin to North Carolina to ... anyway, to demonstrate that I'm going out in the areas where we think we can win."

One reporter quizzed Biden about his 2020 campaign position as a "bridge candidate" to pass the torch to a younger generation.

"What changed was the gravity of the situation I inherited in terms of the economy, our foreign policy and domestic division," he said.

"What I realised was my long time in the Senate had equipped me to have the wisdom to know how to deal with the Congress, to get things done. I got more major legislation passed that no-one thought would happen and I want to finish ... to get that finished."

Asked about the ongoing war between Israel and Hamas in the Middle East, Biden probably hasn't seen off his age-based detractions by reminding reporters about his long association with the region.

Biden reflected on his first meeting with an Israeli leader - Golda Meir.

Israel's first female prime minister was born in 1898 and led the country from 1969-1974. She died in 1978.He also acknowledged that there had been obstacles to the peace process - including Israel's "conservative" war cabinet.

Now Biden's said he is in fact willing to talk to "any leader who wants to talk" - including Putin.

"Last time I talk to him, I was trying to get him on arms control agreement relating to nuclear weapons in space," he said.

"That did not go very far."My point is I'm prepared to talk to anybody but I don't see any inclination. There is not any inclination on the part of the Chinese to keep in contact."

"The only thing age does is create a little bit of wisdom if you pay attention," Biden says.

He's addressed questions about his health, saying he has taken "three significant and intense neurological exams".

"Every single day I'm surrounded by good doctors and if they think there's a problem, I promise you, even if they don't think it's a problem and I think I should have an exam again, I will do it," he said."But no-one is suggesting that to me now."

Biden has said he has "direct access" to Chinese President Xi Jinping to help head off misunderstandings.

"There is a direct line between Xi and me, and our military has direct access to one another, and they contact one another when we have problems," he said.

"The issue is that we have to make sure that Xi understands there is a priceto pay for undercutting both the Pacific basin as well as Europe and it relates to Russia and dealing with Ukraine."

Those fellows from down under - to reach back to another Biden gaffe - have been name-dropped at Biden's presser as he underscored his international achievements.

"I was able to get 50 other nations - five-zero, 50 - to support Ukraine - 50," Biden said.

"We were able to bring about a coalition of Europe and Asia, Japan and South Korea."I just met - we talked about AUKUS and we talkedabout the relationship between Australia, New Zealand, Japan, South Korea and the United States.

"We are making the world safer and stronger because we have to deal with a new arrangement that exists in the world, the Cold War is over, the post war era is over."At the announcement of the AUKUS partnership, Biden appeared to forget the name of then-Prime Minister Scott Morrison, referring to him as "that fellow Down Under".

Biden denies he's been slowing down in the past few years.

"The best way to assure (voters) is the way I assure myself, and that is, am I getting the job done? Am I getting the job done?" he said.

"Can you name me somebody who has gotten more major pieces of legislation passed in three and a half years? I created 2000 jobs just last week.

"If I slow down, I can't get the job done. That is a sign that I shouldn't be doing it. There is no indication of that yet."

Biden appeared to suggest his debate performance and over-stressed schedule was the fault of his staffers.

"I love my staff but they add things all the time at the very end," he said.

"I am catching hell from my wife for that."He then paused before calling on the next reporter.

Biden has pushed back on previous reports he'd acknowledged he needed earlier nights and more sleep following his "stupid mistake" at his debate against Donald Trump.

"What I said was, instead of my every day starting at 7pm and going to bed at midnight, it would be smarter for me to pace myself a little more," he said.

"If you looked at my schedule since I made that stupid mistake in the debate, my schedule has been full bore," he said.

"Where has Trump been? Riding his golf cart and filling out his score card before he hits the ball? He has done virtually nothing."

Trump has indeed been relatively quiet following the debate - or perhaps just out of the media focus for once.

But it's considered a political ploy to allow Biden to continue copping self-generated heat.

"I always have an inclination, whether I was playing sports or doing politics, just to keep going, not stop," Biden said.

"I've just got to pace myself a little bit more. Pace myself. The next debate, I won't travel into 15 time zones a week before."

Biden has repeatedly drawn attention to what he's touting as the achievements of his administration.

He's pointing to falling inflation, a growing economy, his efforts towards peace in the Middle East, and a bipartisan effort on border security he claimed cut illegal arrivals in half.

It's likely an attempt to put eyes on substance rather than style.

Biden's voice grew notably softer and less strident when he stopped reading his prepared speech, but he's been fairly bullish taking on reporters and backing himself in the job.

"I am not in this for my legacy, I am in this to complete the job I started," he said."If you recall, understandably, many of you, many economists thought my initial initiatives that I put forward - you can't do that, it will cause inflation and things will skyrocket and the debt will go up.

"What are you hearing now from mainstream economists? Sixteen economic noble laureates said I have done a hell of a job."

Biden has departed prepared remarks and responding to the first question of the press conference - question from Reuters, accidentally mis-named his own vice-president Kamala Harris.

Asked about what he thought of her capabilities to potentially fill his shoes, Biden said: "I wouldn't have picked Vice President Trump to be Vice President did I think she was not qualified to be President. Number one, I will start there."

He did not correct himself.

Biden has lobbed a shot across the bow at Republican rival Donald Trump, contrasting their attitudes toward America's long-standing allies.

"My predecessor has made it clear that he has no commitment to NATO," he said.

"He has made it clear that he would feel no obligation to honour Article 5.

"Article 5 of the treaty guarantees the military intervention of NATO against aggression towards member countries."(Trump) has already told Putin 'do whatever the hell you want'," Biden said.

"I made it clear, a strong NATO is essential to American security. I believe the obligation of Article 5 is sacred.

"I remind all Americans, article 5 has been evoked only once in NATO's long history and that was to defend America after 9/11. I made it clear that I will not bow down to Putin."

Biden has opened with remarks about the just-concluded NATO summit, which he said members had agreed was "a great success".

"For those who thought NATO's time passed, they got a rude awakening when Putin invaded Ukraine," he said.

"Some of the oldest and deepest fears in Europe roared back to life because, once again, a murderous madman was on the march but this time no-one cowered in appeasement, especially the United States."

Speaking from prepared remarks, Biden's voice appears to be strong and firm, despite a couple of verbal stutters.

We'll bring you the key lines and reaction as it happens. You can watch live at the top of the stage.

This from CNN's Jake Tapper:

A long-time adviser to President Joe Biden says that he's angry and frustrated with the president's inner circle and family over the current situation.

"I just think there is an unfortunate inevitability to all this. I am sad because I have known him a long time and he is a good man. I am angry at his inner circle who have not served him well and at times committed malpractice in their service," the adviser said.

"And I am frustrated at the family for not expanding the circle so there would be a truth teller or two in their midst. They created a perfect storm of an echo chamber and it is biting them all in the ass," they added."

Analysis from Associated Press:

Americans tend to regard their leaders less for what they do than how they make them feel, and Biden's debate disaster has shaken his party to its core.

"The debate was a reminder that you can have as many policies as you want, but what the public sees and hears might matter more," said Julian Zelizer, a Princeton presidential historian.

"Voters may see Biden's frailty as a symbol of weakness or its own kind of instability."

Biden can give a good speech — his State of the Union address earlier this year helped quiet doubters about his viability as a candidate.

But his strength as a president and politician has been how his humanity in intimate settings resonated with voters, and the power of his personal narrative and down-to-earth roots.

Yet those moments, in private or before small crowds, even if amplified on social media as Biden's team hopes, are certain to reach fewer people than the tens of millions who watched his bout with Trump.

A former Biden staffer says the president is "a great patriot, a great American" - even as he called for him to leave the White House race.

Jamie Metzl, who has worked for the Biden and Clinton administrations, said Biden had been an "excellent" president".

But there's just a time - as painful as it is - when we take the keys away from our parents, when we recognise that that somebody's brain is changing," he told Today.

"And that's what's happening here. And as much as I love the guy, it's just not possible to imagine he'll be capable of being president of the United States for another four and a half years."

Even before the debate, Biden has held fewer press conferences than his most recent predecessors.

Biden has held 36 press conferences thus far in his presidency, fewer than former presidents Donald Trump, Barack Obama and George W Bush at the same point in their presidencies.

While the White House has countered that Biden has held more off-the-cuff interactions with the press than his predecessors while traveling to events and meetings, reporters say those are nowhere near the same as an open format press conference.

US President Joe Biden will take on all comers in a promised press conference this morning.

The embattled Democrat has had a fortnight to forget after stumbling in a debate performance against Republican rival Donald Trump in late June.

While polls show Biden took less of a hit with voters than was anticipated, his poor showing has been roundly savaged by observers and the media, and growing calls from one-time supporters that he should vacate the race for the White House.

There has been open speculation about his acuity and ability given his age of 81 - a few years older than Trump at 78.

For his part, Biden has acknowledged his fumble, but maintained he's the man to beat Trump in November.

Now, perhaps in an effort to prove his facilities are intact, Biden will front reporters at the White House in a free-form press conference.

It's awkward timing for POTUS after a new gaffe this morning saw him verbally confuse Ukrainian President Volodymyr Zelenskyy with Russian leader Vladimir Putin - the man invading Zelenskyy's country.

The timing of the presser has been pushed back to 9am-9.30am AEST.