US election live updates: Kamala Harris makes first public ...

If you've been deep in US politics news for a little while, the how-we-got-here perhaps feels like a bit of a blur.

The momentum behind a movement to convince Joe Biden to step aside and let someone else contest the 2024 presidential election was swift, and things really came unglued at the disastrous debate on June 27.

Former North America correspondent Kathryn Diss and our international digital editor Rebecca Armitage have charted the chaos that unfolded over the past few weeks.

If Kamala Harris secures the Democratic nomination, she'll need a running mate.

The vice-presidential pick is usually a strategic one, aimed at broadening a candidate's appeal among voters from particular backgrounds or geographical areas.

Speculation around who could join a Harris ticket has so far centred on potential rivals for the nomination who were quick to endorse her bid.

Pennsylvania governor Josh Shapiro is considered a rising star in the party and represents a swing state that could be critical to the Democrats' chances of winning the election.

Former presidential candidate and now Transportation Secretary Pete Buttigieg has a national profile and personal ties to another closely fought state, Michigan.

While Kentucky governor Andy Beshear has found political success in a state otherwise dominated by Republicans.

It's still early days, as Harris isn't yet guaranteed to be the nominee.

But we can expect chatter around her potential VP pick to intensify in the days ahead.

ABC's Michael Rowland has spoken to former US ambassador to Australia Jeff Bleich.

He told Rowland he thought Joe Biden stepped down for "all the right reasons".

"I thought it was an extraordinary act of statesmanship, and the kind of act I would expect from Joe Biden, which was putting Americans' interest ahead of his own," he said.

He praised Kamala Harris as a candidate, and said he was expected to meet with the vice-president and Biden in California on Saturday, local time.

Watch the full interview here:

Several Democratic committee members asked Secret Service director Kimberly Cheatle earlier today about how widespread access to the types of weapon that the shooter used in Pennsylvania made the job of her agents more difficult. 

Thomas Matthew Crooks shot the Republican presidential candidate with an assault rifle-style weapon capable of firing multiple rounds in quick succession. Cheatle confirmed media reports that it was a serial number on the AR15 Crooks was carrying that led to him being identified.

Democratic committee member Gerry Connolly asked Cheatle several times whether "the ubiquity of guns in America, especially assault weapons or semi-automatic weapons" made her job harder or easier.

Cheatle repeatedly avoided answering the question, responding that "the threat environment" for Secret Service agents "is always difficult, and that's dynamic, and it's always evolving".

But Connolly asked again. 

Cheatle: "I think the job of the Secret Service is difficult on every day, and we need to make sure that we are mitigating all threats, whether that be —"

Connolly: "That wasn't my question. And now I think you're evading the answer, which is not a hard one."

Cheatle: "I am sorry that you feel that way, sir."

Connolly: "Well how else could I feel Director Cheatle? When you're clearly avoiding a direct answer to a very simple declarative question? We almost lost a presidential candidate the other day. A 20-year-old had access to his father's AR-15 and got on top of a roof within 500 yards or feet of the podium. And I'm asking you, did the availability of that AR-15, which is replicated all across America, make your job harder or easier? And you're not willing to answer that question. And you wonder why we might have a lack of confidence in your continued ability to direct this agency."

Cheatle: "I understand your question, and that's the environment."

Connolly: "Well, if you understand my question, why not answer it?"

Cheatle: "Because it's the environment that the Secret Service works in every day."

The Harris campaign has released some figures in response to the record-breaking $US81 million small-town donations received through ActBlue.

In the last 24 hours:

The following is a statement from Harris for President spokesperson Kevin Munoz:

"The historic outpouring of support for Vice-President Harris represents exactly the kind of grassroots energy and enthusiasm that wins elections. Already, we are seeing a broad and diverse coalition come together to support our critical work of talking to the voters that will decide this election."

Speaking in Delaware, Kamala Harris told her supporters that building up the middle class will be a defining goal of her presidency and that she believes in a "brighter future that makes room for all Americans".

She criticised Donald Trump, who she says "wants to take us backward to a time before many of our fellow Americans had freedoms and rights".

"We believe in a future where every person has the opportunity to not just get by, but get ahead. 

"We believe in a future where no child has to grow up in poverty. Where every person can buy a home, start a family, and build wealth. And where every person has access to paid leave and affordable child care.

"That's the future we see." 

Here's more of her speaking from KamalaHQ:

Expect to see a lot more of Kamala Harris's husband, Doug Emhoff, in the weeks and months ahead.

The second gentleman paid tribute to Joe Biden, as he introduced Harris to the podium at campaign headquarters in Delaware.

"We are going to win this election," he told the assembled staff.

"We are on the right side of every single issue."

Emhoff is a former lawyer who moved from the east coast to California as a teenager and married Harris in 2014.

The 59-year-old is the first Jewish spouse of a US president or vice-president, and has partly focused his role on trying to combat anti-Semitism.

He has two adult children, Cole and Ella Emhoff, from his previous marriage.

When Harris married their father, they decided they didn't like the term "step-mum".

"Instead they came up with the name 'Momala,'" Harris wrote in 2019.

Emhoff is the first ever husband of a female vice-president.

If Harris wins the Democratic nomination, and then the election, it would be the first time there was a first gentleman in the White House.

The vice-president had nothing but praise for Joe Biden while speaking in Delaware.

"We love Joe and Jill. We really do. They truly are like family to us," Harris said.

"It's mutual," Biden replied via phone call.

Harris added that it has been one of the "greatest honours" of her life to serve as vice-president alongside Biden. 

Here's some more of what Joe Biden had to say earlier. He called into this campaign event from home, where he's still isolating with COVID. Sounds like he's promising to get back on the campaign trail to support his VP as soon as he can.

"If I didn't have COVID, I'd be standing there with you. I'm so proud of what you've all done. And this COVID's keeping me out of people's hair for the next three or four days, but I'm going to be on the road. I'm not going anywhere," he said.

He addressed Kamala Harris directly, just before she spoke:

"I want to say hello to Kamala, she can hear me … and I want to say to the team, embrace her, she's the best.

"I know yesterday's news is surprising, and hard for you to hear. But it was the right thing to do."

Biden says he's going to be "working like hell", both as a sitting president and campaigning on behalf of Harris.

"I'm still going to be fully engaged. I've got six months left in my presidency, I'm determined to get as much done as I possibly can."

We've got a new catch cry from the Kamala Harris campaign.

In her closing comments she engages the staff in a call and response.

"Do we believe in freedom? YES. Do we believe in opportunity? YES. Do we believe in the promise of America? YES. And are we willing to fight for it? YES. And when we fight? WE WIN."

She goes on:

"As a young prosecutor, when I was in the Alameda County District Attorney's office in California, I specialised in cases involving sexual abuse. Donald Trump was found liable by a jury for committing sexual abuse.

"As attorney-general in California, I took on one of our country's largest for-profit colleges and put it out of business. Donald Trump ran a for-profit College, Trump University, that was forced to pay $25 million to the students it scammed.

"As district attorney, to go after polluters, I created one of the first environmental justice units in our nation. Donald Trump stood in Mar-a-Lago and told Big Oil lobbyists he would do their bidding for a $1 billion campaign contribution."

Now that Kamala Harris is Donald Trump's likely rival for the presidency, the Harris camp is framing the race as "prosecutor vs felon". (Harris used to be a top prosecutor in California; Trump was recently convicted of 34 felony offences in New York.)

Speaking at the campaign event in Delaware, she said:

"I took on perpetrators of all kinds.

"Predators who abused women, fraudsters who ripped off consumers, cheaters who broke the rules for their own gain.

"So hear me when I say I know Donald Trump's type.

"And in this campaign, I will proudly put my record against his."

The vice-president is surrounded by cheering staffers ready to run the campaign in the coming months.

"We have 106 days until election day and in that time we have some hard work to do," she says.

Harris says she's asked Jen O'Malley Dillon, who's been running the Biden campaign, to stay on as leader.

"As JOD always reminds us, we can do hard things. JOD has been such an incredible leader of this team and that's why I've asked her to run my campaign and she has accepted," Harris said.

"We are going to take our case to the American people and we are going to win!"

Kamala Harris's husband Doug Emhoff gets a warm welcome from the crowd as he introduces the vice-president.

"We have an amazing team and you've done an amazing job, and we're gonna continue to do that so we can make Kamala Harris the next president of America!"

And it's over to Harris.

She gives a shout-out to Joe Biden, still on the line apparently.

"I knew you were still there Joe!"

Kamala Harris is visiting campaign staff in Delaware.

She's about to give a speech. But Joe Biden, who hasn't been seen or spoken publicly since he went into COVID isolation last week, has given some remarks by phone first.

He's urged the campaign staff to "give every bit of your heart and soul that you gave to me to Kamala", and promised to do whatever she wants or needs him to.

As we've seen time and time again over the past few weeks, US politics is unpredictable — and anything could happen!

But it's looking increasingly likely that Kamala Harris will become the Democratic candidate at November's election.

President Joe Biden gave her chances a huge boost when he endorsed her, straight after announcing that he was stepping aside.

Former House speaker Nancy Pelosi, who's still considered very influential within the party, has also now backed the vice-president.

And the people who had been considered Harris's main potential rivals for the nomination — including governors Gavin Newsom, Gretchen Whitmer and Josh Shapiro — have all lined up to support her.

Not all prominent Democrats are on the same page.

As my colleague Brad Ryan noted below, former president Barack Obama has suggested there should be an open contest, while congressional leaders Hakeem Jeffries and Chuck Schumer haven't offered their public endorsement.

But at this stage at least, there's little sign of anyone else stepping forward to challenge Harris.

And that, along with the large amount of money raised in the time since she emerged as the frontrunner, suggests she could be hard to beat.

More than $US230 million has been raised for Kamala Harris in the first 24 hours of her campaign.

Yep, you heard that right.

Yesterday, we saw millions of dollars of donations flooding from small-town donors through ActBlue, the major Democratic Fundraising platform.

Kamala HQ has announced that number has now hit $US81 million (or $121.9 million).

It was the largest single day of campaign fundraising of any candidate in US history. 

Future Forward, the largest political action committee in Democratic politics, secured $US150 million in commitments over the same period from donors who were "previously stalled, uncertain or uncommitted," a senior adviser told the Associated Press.

That's a total of $US231 million (or $347.7 million).

News Breakfast co-host Michael Rowland and North America correspondent Barbara Miller have been reporting live from the White House.

Republican vice-presidential candidate JD Vance has hit the campaign trail too, with an event in Middletown, Ohio.

He spent some time wandering down memory lane and sharing recollections from his time at Middletown High School, and told the hometown crowd he'll never forget where he came from.

Another Democratic governor whose name has been touted as a possible contender for the presidential nomination has endorsed Kamala Harris.

Kentucky's Andy Beshear jumped on MSNBC's Morning Joe to announce the VP had his full support.

"[President Joe Biden's] decision I know was hard, but it's going to secure his legacy that I believe historians are going to say was a great presidency," he said.

"With that, I am excited to fully endorse Vice-President Harris for the next president of the United States.

"The vice-president is smart and strong, which will make her a good president, but she's also kind and has empathy, which can make her a great president. And the contrast between her and those running on  the other side couldn't be clearer."