Replacing President Biden as the Democratic nominee would be highly complicated, and likely impossible, unless the president voluntarily decided to back out on his own.

Politically and mechanically, it is nearly impossible to believe that Democrats would or could forcibly prevent Biden from becoming the nominee.

Right now, Biden is the only candidate for whom those attending the Democratic convention can even vote.

He received 99 percent of his party’s delegates in the primaries, and Democratic delegates have pledged to back whoever won their state’s contest in the first round of voting.

Democratic National Committee (DNC) rules require delegates that Biden won to pledge their support for his nomination unless Biden were to willingly decide to stand down and free his delegates for another candidate. 

Before the convention opens on Aug. 19, the DNC could change the rules to block Biden, but that would require a level of political support hard to imagine. A battle between pro- and anti-Biden factions at a convention to unseat him is highly unlikely to happen.

But the possibility is conceivable that party leaders, including former Presidents Obama and Clinton, might be convinced to talk to Biden about dropping out, Democratic sources told The Hill. Biden ultimately puts the most value on advice from first lady Jill Biden and his sister, Valerie, two people who are largely considered the only voices who could truly change his mind.

A situation unique to 2024 may give party leaders even less time to sort out who will be the nominee than they normally would have. Ohio state law requires its ballot to be certified 90 days prior to the election. This year, that falls on Aug. 7, almost two weeks before the convention starts.

Despite Ohio state lawmakers trying to pass a bill to fix the issue, they deadlocked, leading DNC leaders to decide to virtually nominate Biden in advance of the deadline and the convention. If they plan to follow through on this, any change in the nominee would need to happen before Ohio’s deadline if the candidate is to be on the ballot in the state, notwithstanding a fix from Ohio lawmakers.

On Friday, party leaders were coalescing around Biden and not giving any signal that they might privately push for him to drop out.

His campaign, the White House and surrogates have pushed back forcefully on the idea, but others said if polls show his performance is hurting down-ballot candidates, it could become a real subject.

Who could replace him?

The natural successor to Biden would be Vice President Harris.

But she wouldn’t be the automatic replacement, if Biden were to drop out.

While Biden won the primaries, his support won through those contests cannot be bestowed by Biden on Harris.

Harris would instead, at the convention or sooner, compete with other potential candidates who might see themselves as stronger candidates than the vice president against presumptive GOP nominee, former President Trump.

According to its bylaws, the DNC has general responsibility for the affairs of the party between national conventions, and those responsibilities include filling vacancies in the nominations for the office of the president and vice president.

If Biden exited, there would be a vacancy.

And Harris would be the logical successor.

Politically, some said it was hard to believe, at this stage, that someone could replace Harris if Biden wanted her to be his replacement on a ticket. But there would almost certainly be prospective politicians, such as California Gov. Gavin Newsom or Michigan Gov. Gretchen Whitmer, who might try.

“This is the bigger pickle to replacing Biden. I don’t see the Democratic coalition surviving intact if Harris is not on the top of the ticket, and it’s hard to assure that would be the party consensus if they replace Biden,” a former DNC official said.

If there were more than one Democratic candidate vying to replace a withdrawn Biden as the party’s nominee, those prospective candidates would likely need to fight it out with state delegations at the August convention in Chicago.

This would set up a scenario that hasn’t been seen in American politics in decades: A contested convention that actually selects the party’s nominee.

Conservative groups have suggested they will file lawsuits around the country, potentially questioning the legality of the Democratic candidate’s name on the ballot, in such a situation.

But in an interview with the Associated Press, Elaine Kamarck, a senior fellow in governance studies at the Brookings Institution in Washington, noted the courts have consistently stayed out of political primaries as long as parties running them weren’t doing anything that would contradict other constitutional rights, such as voter suppression based on race.