US Vice-President Kamala Harris has passed the threshold to clinch the Democratic presidential nomination in a vote of party delegates.

Speaking by telephone, Ms Harris said she was "honoured to be the presumptive nominee" as the virtual roll call continues ahead of the Democratic National Convention (DNC) in Chicago later this month.

Ms Harris is the first black woman and first South Asian woman to become the White House standard-bearer for a major US political party.

If she defeats Donald Trump, the Republican nominee, in November she would be America's first female president.

She ran unopposed in the virtual roll call after President Joe Biden stepped aside last month and quickly endorsed her. Several potential rivals followed his lead.

On Friday afternoon, Ms Harris formally became the nominee after securing the support of 2,350 delegates, the threshold required to earn the nomination.

"We believe in the promise of America and that’s what this campaign is about," she said in brief remarks by phone as she crossed the benchmark.

"We are in this, we are on the road and it's not going to be easy, but we’re going to get this done."

In total, Democrats have said 3,923 delegates - or 99% of the participants - plan to vote for her.

The rollcall began on Thursday and ends on Monday.

Presidential and vice-presidential nominees are typically anointed at their party conventions, but the relatively late date of the 2024 DNC risks falling afoul of state ballot access laws.

Ms Harris, 59, was born in Oakland, California, and is the first Democratic nominee in the party's nearly 200-year history to hail from a western state.

She rose through the ranks of state politics from San Francisco district attorney to California attorney general and then US senator.

Before dropping out of the race, Mr Biden had easily won the Democratic primary. He did not face stiff opposition despite voter concerns about his age and had won backing from 99% of pledged DNC delegates.

But the 81-year-old faced escalating pressure from within the party to withdraw after a poor June debate performance against Trump.

The decision to hold a virtual nominating process ahead of the 19-22 August convention was made while Mr Biden was still the presumptive candidate.

It came in response to rules for ballot access in the state of Ohio, which requires that candidates for the November ballot be formally selected 90 days before the election - or by 7 August.

Republican leaders in the state had warned they would enforce the law and, though lawmakers eventually created an exemption as they have done in the past, Democrats said an early rollcall would pre-empt further risks of their candidates being excluded from the ballot.

Delegates do not need to vote on the vice-presidential pick.

Ms Harris is expected to name her running mate by Monday.

The Trump campaign and some Republicans have criticised the replacement of Mr Biden with Ms Harris, arguing she is the first major party candidate to secure the nomination without holding a press conference or a sit-down interview. Some have referred to the substitution as a "coup".

But Ms Harris has hit the campaign trail hard since Mr Biden's endorsement, making the case against Trump in multiple campaign rallies and fundraisers across battleground states.

On Friday, the campaign announced it had raised more than $310m (£242m) in the month of July, with more than two-thirds of people donating money for the first time.

That figure is more than double the $138m raised by the Trump campaign last month and marks the biggest haul of the 2024 election cycle so far.