Thanks for joining us today, as we conclude today's coverage of the uncertainty surrounding President Joe Biden's reelection bid.

We've covered a lot of ground today with members of Congress returning to Washington, the president pushing back on calls for him to drop out from the race, and dozens of foreign officials arriving in the US capital for the Nato summit - which begins tomorrow.

We'll be ending our live coverage for now, but here is a summary of what happened during a busy day in US politics:

• Biden phoned MSNBC's Morning Joe - an influential news programme that he reportedly watches daily - to reiterate that he is "firmly committed to staying in this race" and dared other Democrats to challenge him at the convention
• In an open letter to Congressional Democrats, Biden remained defiant and added: "We have one job. And that is to beat Donald Trump"
• He also reassured donors and supporters on a call this afternoon: "I'm not going anywhere and I'm going to beat Trump"
• But reporters peppered administration officials at a heated press briefing for clarification on media reports about neurological specialists visiting the White House
• Press secretary Karine Jean-Pierre rejected speculation the president is or has been treated for neurological disorders, and national security spokesman John Kirby said last month's debate was "not reflective" of the president's abilities
• Democratic members of Congress gave Biden mixed reviews, with some expressing support and others - like Senator Joe Manchin - suggested the issue needs "a couple of weeks to mature"
• But senior House Democrat Adam Smith said it would be "a mistake" for Biden to stay on, urging him to step aside "as soon as possible"
• Biden will talk to, and field questions from, the influential Congressional Black Caucus, a key backer on Capitol Hill, later this evening

Thanks again and keep following BBC News for the latest.

Image source, Getty Images

Adam Smith, a senior House Democrat, has publicly called on Joe Biden to end his candidacy "as soon as possible".

He said the president should release his delegates so that Democrats can nominate someone new at the party convention in August.

"Any candidate for the highest office in our nation has a strong burden to bear. That candidate must be able to clearly, articulately, and strongly make his or her case to the American people," he wrote.

"It is clear that President Biden is no longer able to meet this burden."

The Washington congressman is the top Democrat on the House Armed Services Committee and a leading voice in Congress on national security matters.

Smith said Biden's debate performance was "alarming to watch" and said he had "not seriously addressed" voters' concerns since then.

The congressman hedged his statement stightly by saying that he "will back him (Biden) one hundred percent and without reservation" if he is the nominee.

But he concluded by saying that if "the President continues his campaign, it would be a mistake."

Joe Biden will meet with the entire Congressional Black Caucus (CBC) on a Zoom call this evening to discuss his candidacy.

Sources told CBS News, the BBC's US partner, that the president intends to talk about the stakes of the upcoming election and their intentions to defeat Donald Trump.

Biden will also take questions.

The president has personally called several members of Congress since his poor debate performance, a Biden campaign official told CBS News. He has since released a letter to Democrats this morning that says he remains "firmly committed" to running for re-election.

The CBC boasts 55 members - all Democrat - in the House of Representatives and three in the Senate. The highly influential body includes Minority Leader Hakeem Jeffries and top Biden ally, Congressman Jim Clyburn of South Carolina.

Biden has long touted the support he has earned from the black community, especially in his 2020 race for the White House. Recent polls suggest that support may have weakened ahead of the upcoming election.

Madeline Halpert
US Reporter

Several delegates to the Democratic National Convention have expressed unequivocally that their support for Biden remains unchanged - despite calls for him to drop out of the race.

These delegates will cast votes for Biden at the August event in Chicago, which will make him the official nominee. They are obligated to support Biden by "good conscience" after he won the Democratic primary, according to party rules.

At age 22, Elijah Hooks is one of the youngest delegates to the DNC from Florida, where he is actively involved in the state's Democratic Party.

He says Biden's debate performance was rocky, but "we all make mistakes".

"I'm fully behind President Biden," Hooks says, adding that he would be open to other candidates - particularly Vice President Kamala Harris - only if Biden decides he no longer wants to be in the race.

There are 3,939 delegates who come from all 50 US states to attend the DNC. Some are as young as 18 and others are in their 80s, but nearly all are pledged to Biden after he won the popular vote in their state primaries.

Another delegate, Leo Bortolotto of Denver, says he is looking forward to casting a vote for Biden.

When asked whether he had concerns about Biden's age, he says he has "no comment".

Sally Simpson, the vice chair of the Kenosha County Democrats in Wisconsin and a convention delegate, also maintains her support for the president and adds that the media "haven't done to Trump what they've done to Biden".

She says she has started to consider what would happen if another candidate jumped into the race, but is unsure who she would support.

Image source, Getty Images

As the Senate returned to work today, Democratic lawmakers in the chamber have appeared mixed about whether or not Joe Biden should stay in the presidential race.

Dick Durbin, a senior Democrat from Illinois, told reporters he remained confident that Biden could win reelection, but he noted that the debate "raised a lot of questions" that the president is working to answer.

"In some respects he's done it very effectively. In other respects, not so effectively."

Joe Manchin, a West Virginia Democrat who has butted heads with the Biden administration, said the press and the public needed to give the issue "a couple weeks to mature". He noted, however, that their concerns about the president's performance were "valid".

Virginia Senator Mark Warner reportedly planned to huddle with colleagues to discuss Biden's path forward, but that meeting was cancelled after it leaked to the media.

Instead, the Democratic lawmaker issued a statement saying "now is the time for conversations about the strongest path forward" to prevent a second Trump term.

He called on Biden "to more aggressively make his case to the American people, and to hear directly from a broader group of voices about how to best prevent Trump’s lawlessness from returning to the White House".

After concern over Biden's candidacy grew over the weekend, a number of Democrats have come out in support of the president's reelection campaign when they returned to Washington today.

Pramilia Jayapal, the chair of the Congressional Progressive Caucus, released a key statement assuring voters on the left that they should continue to back Biden.

Echoing the president's frequent statements on the campaign trail that the "foundation of our democracy is at stake", she noted the administration's "remarkable accomplishments" and the need to defeat former President Donald Trump.

Several other lawmakers have shared similar sentiments since Congress returned to Washington.

Congresswoman Grace Meng of New York called on fellow Democrats to stop Trump by focusing on "re-electing President Joe Biden and Vice President Kamala Harris".

Meanwhile, Senate Majority Leader Chuck Schumer pushed back on speculation around his support, telling reporters: "As I've said before, I'm for Joe."

The BBC's US partner, CBS News, is reporting that the president reassured donors on a phone call this afternoon that he was staying in the race.

“My one job is to beat Donald Trump,” Joe Biden said.

“I’m not going anywhere and I’m going to beat Trump."

Sources told CBS that Biden said he was done talking about the debate and will shift to an "attack, attack, attack" strategy focused on his rival and the Republican agenda.

Kayla Epstein
Senior journalist

The Biden team has launched an all-out political battle to counter last week's panic over his debate performance. While the president is by no means in the clear, their strategy seems to have at least held the line today.

Their unwavering message: Biden is not dropping out.

Biden - appearing to take a page out of Donald Trump's playbook - called in to give a live phone interview to MSNBC's Morning Joe, an influential political TV programme this morning.

His team privately circulated a memo to Democratic members of Congress on Sunday intending to shore up support, The Washington Post reported.

The president blasted out a public letter to Congress this morning making it absolutely certain that he was staying in the race.

Then later, White House spokeswoman Karine Jean-Pierre forcefully pushed back against intense questions from reporters on the president's health.

It's a pivotal moment for Biden, who needs to snuff out as much doubt as he can this week and convince the party to rally behind him for the final stretch of the election. If he fails, the divisons within the party could dog him all the way to the polls in November.

Bernd Debusmann Jr
Reporting from the White House

Image source, EPA

After more than an hour, an occasionally tense and combative White House press briefing came to an end.

As a storm cloud hangs over Biden's reelection campaign, reporters asked numerous questions of Press Secretary Karine Jean-Pierre and national security spokesman John Kirby.

If you're just joining us, here are a few of the main points from the briefing - which largely focused on the president's health.

• Kirby pushed back on questions about his own experiences working with the president, saying that his debate performance against Trump was not "representative" of a leader he has found to be "sharp"
• The White House also faced questions on whether Biden has been subject to medical examinations, with Jean Pierre clarifying he has regular "check-ins" with his doctors
• She added that his neurological exams - part of his regular physical - have been "reassuring" with no findings that suggested any ailments
• Tensions flared after the White House declined to confirm the names of specialists who have visited the White House, citing privacy and security concerns
• Senior CBS News correspondent Ed O'Keefe nearly shouted at Jean-Pierre, who he believed was dodging questions about the visits
• Additionally, the White House confirmed that Biden has spoken to some senior Democrats on Capitol Hill, including Senate Majority leader Chuck Schumer

The White House Press briefing just concluded, but at the end Karine Jean-Pierre pushed back against questions about President Biden's health.

Several reporters asked about a Parkinson's disease specialist visiting the White House multiple times. She rejected speculation that Biden might be receiving treatment for the disease.

"Has the president been treated for Parkinson's? No. Is he being treated for Parkinson's? No." she said.

The New York Times reported that an expert on the disease from Walter Reed National Military Medical Center in Washington had visited the White House eight times since last year.

Citing the need to "protect the privacy" of the doctor and "security reasons", Jean-Pierre would not specifically comment on his visits to the White House.

She noted, however, that medical professionals and military personnel often have reasons unrelated to the president to visit the grounds.

Bernd Debusmann Jr
Reporting from the White House

White House Press Secretary Jean-Pierre was just asked whether President Biden is willing to take a cognitive test to "rule out" whether anything is amiss with President Biden's test.

Echoing Biden's own words in an interview last Friday with ABC, she said that Biden has said "multiple times" that "everything he does" on a day-to-day basis is a cognitive test "as it relates to delivering for the American people".

Jean-Pierre - now clearly bothered - has also taken umbrage to suggestions that she or the White House is withholding information about the president from reporters.

"I appreciate the back and forth that we have. I try to respect you, and to help you...we literally do everything that we can to make sure to get answers to you," she says. "That's a democracy."

"I will be the first to admit, sometimes I get it wrong," the press secretary adds. "But I do take offense to what was just happening at the beginning of this meeting."

Jean-Pierre also insists that, despite speculation, there was no script when Biden called into a news show on MSNBC this morning.

"He spoke from the heart," she says. "I think it was incredibly powerful."

Bernd Debusmann Jr
Reporting from the White House

Image source, Getty Images

It's all of a sudden gotten slightly tense in the briefing room, with an increasingly exasperated Karine Jean-Pierre fielding questions from increasingly exasperated members of the press.

"A little respect, please," Jean-Pierre says. The exchange draws some nervous laughter in the back of the room.

"Every time he has a physical, he has had to see a neurologist," Jean-Pierre emphasises to reporters to a slew of questions about reports that the president met with specialists. "That is answering that question."

Jean Pierre also took a thinly veiled swipe at Donald Trump, saying that Biden has done more than "the other guy", and that his check-ups and released information are in line with those of the Obama and Bush administration.

Tensions flared when Jean Pierre was asked if the White House could release the name of the specialist that saw Biden.

"We cannot share a name. No. No. No," she said. "It doesn't matter how hard you push me. It doesn't matter how angry you get. I'm not going to confirm a name. It doesn't matter if it's even in the log."

Bernd Debusmann Jr
Reporting from the White House

Karine Jean-Pierre is now up, and immediately took a question on whether President Biden had a "medical examination" - a question that was the source of considerable discussion last week.

According to the White House press secretary, Biden had a "check in", which she described as a regular, verbal check-up in which a "a couple of words" were exchanged with a White House doctor.

"He did not have a medical exam," she clarified.

Another reporter asked about a neurological specialist who has reportedly visited the White House several times.

In response, Jean-Pierre quoted from a neurological exam that was "reassuring" as "there were no findings" of multiple cognitive ailments.

The White House spokesperson noted that she could only confirm he was visited by nuerologist for the president's official physicals.

That answer did not appease reporters, who pushed back on the Jean-Pierre and her answer.

Bernd Debusmann Jr
Reporting from the White House

Image source, EPA

While Kirby has fielded questions on a variety of other topics - such as the war in Ukraine, Nato funding and ongoing negotiations regarding Gaza - the press briefing has often shifted back to perceptions of Biden and the election.

Asked again about his own meetings with Biden, Kirby says he finds it "uncomfortable" answering these questions as a spokesperson and adviser to the president. He adds, however, that he has "no reason to doubt" Biden's cognitive abilities.

Kirby specifically mentioned Biden's "grasp of concepts" and "probing nature" to show that he is "completely in charge of facts and figures".

"It happened to me this morning," Kirby said.

Bernd Debusmann Jr
Reporting from the White House

Kirby was just asked about his own interactions with the president, and whether he had noticed anything amiss during his meetings with Biden.

He again pushed back on the question, claiming that he does not believe that the debate versus Trump in June was "representative" of his interactions with the president.

Kirby also said that in late-night briefings, Biden has seemed sharp and has asked him challenging questions he does not always have answers to.

Clearly, Kirby has come prepared for these questions and is ready to defend Biden from any pointed press questions.

Bernd Debusmann Jr
Reporting from the White House

The briefing is underway here at the White House, and from the very first moment, Press Secretary Karine Jean-Pierre and national security spokesman John Kirby have pushed back on the negative perceptions around Biden's shaky debate performance and the calls for him to step aside.

Jean-Pierre gave a lengthy introduction outlining some of the president's recent moves, upcoming schedule and recent policy accomplishments.

After Kirby shared the latest on the Nato summit, he faced the first question. It was - perhaps predictably - about Biden's interactions with other alliance leaders following what the reporter called a "disasterous" debate performance.

That's no surprise. It's been all that reporters have been discussing since I got here a few hours ago.

Kirby quickly pushed back on the question, saying it "pre-supposes" that US allies need to be re-assured. He said he "is not aware" of any conversations that have taken place on the topic in recent days.

"This president has invested in allies and partnerships," he said, adding that major non-NATO allies "would not be coming" if they did not believe in Biden's abilities.

The leaders of Australia, Japan, New Zealand and South Korea - countries that are not members of Nato - are also attending the summit.

The White House has brought out national security spokesman John Kirby to brief reporters about the upcoming NATO conference.

He spotlights the Biden-Harris administration's committment to strengthening the alliance.

He also said that Biden would take questions from the press at some point in what Kirby dubbed a "big boy press conference". That was a reference to a cheeky reporter question, external from earlier this month, which used that phrase.

Kirby also provided an update on the situation in Ukraine, and said this week's NATO conference would send a "strong message to Putin".

White House Press Secretary Karine Jean-Pierre has just started the daily news briefing.

She is sharing information about recent economic news and highlighting elements of President Biden's schedule - emphasising how busy it has been.

You can watch right here by clicking "Watch live" at the top of this page.

Follow along with us here for more from the White House.

Kayla Epstein
Senior journalist

Senator Cathrine Cortez Masto, a Democrat representing the western state of Nevada, has come out in support of Biden.

"Joe Biden won the Democratic nomination in a landslide because he fights for working people in this country," she posted on X. "He's always had Nevadans' backs, whether it's on the picket lines, protecting our personal freedoms, or lowering costs - now it’s time for us to have his."

Nevada is an important state for Democrats in this election, with its powerful voting blocs of Latino voters as well as union organising.

But it's also a state Republicans are trying to pick up this year.

Cortez Masto very narrowly won reelection against a Republican opponent in 2022, and her Democratic colleague from Nevada - Jacky Rosen - faces a difficult path to reelection in November.

Bernd Debusmann Jr
Reporting from the White House

We've just heard from the White House that the briefing has been delayed until 14:00 local time (1900 BST), 30 minutes later than planned.

There's nothing unusual about this. In my experience, briefings here rarely start on time.

As a reminder, we'll also be hearing from national security spokesman John Kirby in addition to Press Secretary Karine Jean-Pierre.

Stay with us for more updates.