Biden has pulled out – so what happens now? How can he be replaced?
We are in uncharted territory as no serving president who was due to re-stand as a candidate has ever pulled out at this stage. This is what might happen in the coming weeks.
Joe Biden has succumbed to pressure to stand down as the Democratic presidential candidate – so how could he be replaced and how might it work?
A national US party has never tried to force an election candidate to step down in the modern era.
Consequently, we are in uncharted territory, with no clear guide as to what the Democrats will need to do in order to find an alternative presidential candidate.
The voting in the state primaries confirmed Mr Biden as the pick for November’s election.
The 81-year-old won nearly all delegates and he was due to be confirmed as the candidate at the Democratic National Convention in late August.
However, unlike the Republican party, Democratic delegates are not tied to a candidate. The only command to delegates under current convention rules is to “in all good conscience reflect the sentiments of those who elected them.”
That means those Democratic delegates can do whatever they want.
That said, Biden’s campaign played a big role in picking them, choosing supporters for their loyalty.
It’s likely that Mr Biden’s endorsement of vice president Kamala Harris will have some sway with these members – but it’s not a directive.
Mr Biden will now serve out the rest of his presidency and stay in the White House until the incoming leader takes over in January.
But the Democrats will have to come up with a replacement in the coming weeks.
But how will his replacement be chosen?
There will likely now be a frenzy among Democrats as there’s no protocol to choose a new candidate before the convention which starts on 19 August.
It takes a majority of the party’s 4,000 or so delegates to win the nomination – and Mr Biden secured about 3,900 in the primaries.
As leader of the party, he may have some influence over the process – and has already given his support for his vice president Kamala Harris – but it could become a “free for all” with candidates campaigning aggressively to win their vote at the convention.
The party will be extremely keen to avoid scenes of infighting months out from the election – however, it could prove unavoidable.
What is not clear is whether the Democrats will wait until the convention to put those in the frame on show or whether they will work out some way of ensuring the potential nominee is decided before the convention so delegates rally around the chosen pick.
Could Kamala Harris become the new pick?
The vice president was touted as the favourite if Mr Biden ditched his re-election bid, and he has now thrown his support behind her.
However, his delegates will not transfer to her automatically and she will have to compete for their vote with any other hopefuls that come forward.
Soon after Mr Biden made his announcement, Reuters reported Ms Harris’ team had begun calling delegates to get their support.
In addition to the 4,000 delegates, there are also more than 700 so-called superdelegates, including party leaders, certain elected officials and former presidents and vice presidents.
Mr Biden’s campaign recently said it had funds of $91m (£70m). Allied Democratic campaign committees increase it to more than $240 million (£185m).
While the situation has never arisen in modern history, and the law is untested, most campaign finance experts believe that Harris has the right to the Biden campaign’s bank account because her name was on the ticket as well.
It’s possible someone may argue she shouldn’t have the right, but the bottom line is: She just did.
On Sunday evening, the Biden campaign filed to change its name to Harris for President with Kamala Harris as the authorized candidate. That would give her control of the finances – and most experts believe she has that right.
If the Democrats do choose someone other than Ms Harris, party accounts could still benefit the nominee, but the Biden-Harris account would have more restrictions on it, the AP news agency reported.
Recent polls suggest Ms Harris would fare about the same as Mr Biden in the election, but still ultimately lose to Donald Trump.
Read more about her here.
Who else could enter the race?
Two names frequently mentioned were California governor Gavin Newsom, 56, and Michigan governor Gretchen Whitmer, 52.
They didn’t enter this year’s primaries but have both been talked about as potential presidential nominees in future.
Since Mr Biden’s announcement, Mr Newsom has endorsed Kamala Harris as the presidential pick, calling her “tough”, “fearless” and “tenacious” and saying “no one is better to prosecute the case against Donald Trump’s dark vision”.
Read more:
As Joe Biden steps aside, who will replace him?
Ms Whitmer, a lawyer and former prosecutor, was the Senate’s first female Democratic leader and became governor in 2018.
She also served as co-chair of Joe Biden’s 2020 election campaign.
She has also tweeted since Mr Biden’s announcement and was non-committal, giving her support to the process, rather than any one person.
But with Mr Trump ahead slightly in the polls, could she be convinced to go ahead? And will anyone else throw their hat in the ring.
Others mentioned as potential nominees include Kentucky governor Andy Beshear and Illinois governor JB Pritzker
Interestingly, former first lady Michelle Obama – seen as a long shot this time around – would beat Trump and outperform Mr Biden, Mrs Harris and all the other likely replacements, according to a recent Reuters poll.