Can Joe Biden be replaced as the Democrats’ presumptive candidate for November’s US presidential election?
Murmurs around his ability to defeat Republican Donald Trump, 77, in a rematch have only grown louder after a special counsel investigation said President Biden portrayed himself as an “elderly man with a poor memory”.
But with America speeding down the road to the 2024 election, and Mr Biden, 81, dominating the race for the Democratic Party nomination, what happens if he decides to withdraw – or others try to make that choice for him?
Despite weak poll numbers and questions, including from some Democrats, about his age, Mr Biden has stuck to his plan to seek a second term after clearing the field of serious Democratic primary challengers when he announced last year that he was running again.
Minnesota’s Dean Phillips is the only other candidate for the nomination on the ballot, but he isn’t thought to present a serious challenge or have a high enough profile.
The first few state primaries for the Democrats have already taken place – New Hampshire, South Carolina and Nevada.
President Biden won all three, meaning the delegates for those states are for now backing him – although New Hampshire’s are slightly different.
What’s more, the deadline for candidates to be registered for many of the remaining 47 states has already passed.
There are 12 states still with time on the clock for a potential new entrant to the Democratic race, but three of those expire on Friday – Connecticut, Indiana and Maryland.
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So if President Biden were to withdraw, say, this week, there would still be time for other Democrats to get their names on the ballot in some states.
But even if they did, a new entrant in the race would have no way of securing a majority of the delegates at the ballot box.
In that case, the nominee would likely have to be decided at the Democratic National Convention in August.
If this were the case, we may see a broad group of presidential hopefuls such as Vice President Kamala Harris and California Governor Gavin Newsom jockeying to convince the more than 4,000 Democratic delegates to give them the nomination.
“If he drops out before the convention, we will have an old-fashioned convention where the delegates essentially get to make up their mind (on whom to vote for) regardless of who they were elected to represent,” said elections expert Elaine Kamarck, senior fellow at the Brookings Institution in Washington and a member of the Democratic National Committee.
As President Biden’s second-in-command, would the nomination automatically pass to Ms Harris?
Not necessarily. She would likely benefit from their joint campaign infrastructure if she ran for president in his absence, but she has her own popularity issues.
With no heir-apparent to President Biden waiting in the wings, any contest to replace him would be unpredictable.