Following President Joe Biden’s poor debate performance on Thursday night, a number of prominent Democrats are privately hoping he withdraws from the presidential race and gives the party a chance to nominate someone younger who may have a better chance of beating Donald Trump.

But the logistics of any hypothetical attempt to replace Biden are complicated.

Things are different now. At this stage, Biden has locked up enough convention delegates to clinch the nomination, and party elders have no mechanism for forcing him out. He would have to voluntarily withdraw from the presidential race.

Neither Biden nor his campaign has shown any sign of openness to stepping aside. He spoke with defiant exuberance at a campaign rally in Raleigh, North Carolina, on Friday. “I might not debate as well as I used to,” he said. “But what I do know is how to tell the truth.” Former President Barack Obama offered words of support in a social media post linking to Biden’s campaign website.

But if Biden were to change his mind in the coming weeks, it would be simpler if it happened before the Democratic National Convention in August, when his status as the presidential nominee will be official.

If the August 19 convention convenes in Chicago without a presumptive Democratic nominee, the nearly 4,000 pledged delegates would be free to pick a different candidate on the first ballot. And, thanks to reforms passed in 2018, if no candidate achieved a majority on the first ballot, the group of 749 unpledged delegates known as “superdelegates,” which includes all Democrats in Congress and other party dignitaries, would only be able to cast votes on the second ballot.

In the scenario of such a contested or brokered convention, rival candidates for the Democratic nomination would duke it out for the loyalties of state party officers, precinct captains, union leaders, nonprofit officials and Democratic activists.

“It would be very chaotic – like the Wild West out there,” said Casey Burgat, a specialist in political conventions at George Washington University.

Party leaders could seek to steer the process to make it more orderly. Biden himself would likely have the biggest influence, since he could appeal to delegates on the basis that they were previously dedicated to him. Former President Barack Obama has also played a role in corralling disparate party factions in the past.

On the one hand, Obama, Biden and other party leaders lack some of the tools top Democrats wielded before reforms passed after the 1968 election democratized the nominating process.

Party elders in the pre-reform era were able to tap vast state and local-level political machines to overcome ideological and regional differences with promises of patronage jobs and other political perks.

“We have a strong party system playing out in a weak party era,” Burgat said. “There isn’t a strong party cabal or leader or group of leaders who can basically point to a candidate and say, ‘Everyone fall in line.’”

At the same time, the Democratic Party is, relatively speaking, less ideologically divided than it was in the era when segregationist Southern conservatives made up a major party faction.

“The policy differences that exist among Democrats today, while they seem big, are trivial compared to what they had in the past,” said Hans Noel, a presidential nomination process expert at Georgetown University. “And they all agree that they don’t want Donald Trump.”

It would ultimately be up to the individual delegates themselves, however. And in a contest where perceived electability is likely to take precedence, the choices before them would be politically thorny.

Biden’s logical successor is Vice President Kamala Harris, who did a capable job spinning Biden’s performance in a CNN interview last night. As the nation’s first Black, first Asian, and first female vice president, she has made history.

But many Democrats lack confidence in Harris’ ability to win a general presidential election. In 2019, when she ran her own presidential campaign before joining the Biden ticket, her candidacy failed to take off and she ultimately dropped out before any votes were cast.

Harris now rates as only nominally more popular than Biden. The number of voters who disapprove of her job performance exceeds the number of voters who approve of her job performance by 10 percentage points, according to an average of available polls.

Meanwhile, there is a bench of prospective alternatives to Harris — California Governor Gavin Newsom, Michigan Governor Gretchen Whitmer, Illinois Governor J.B. Pritzker, and Pennsylvania Governor Josh Shapiro — who each have their own strengths and weaknesses.

Rejecting Harris, though, would likely alienate Black officials and voters, who are the backbone of the Democratic base. And with the possible exception of Newsom, the other potential contenders would be new to the national stage.

“You’re jumping over someone who would not only be presumptively in that place, you’re jumping over a Black woman, and so that’s going to have all kinds of frustration and spawn a lot of anger among Democrats,” Noel predicted.

There are practical advantages to a Harris nomination as well. Biden would be able to transfer his campaign war chest since she is already part of his presidential ticket.

If it were another candidate, Biden would be able to transfer funds earmarked for the primary, which has concluded, but would have to offer refunds on donations earmarked for the general election. The Democratic National Committee, the joint victory fund and pro-Biden super PACs would be constrained by those limitations.

Biden withdrawing from the race after already accepting the nomination at the Democratic National Convention would be even trickier.

It would be up to the Democratic National Committee to name a replacement, and it’s not clear if that responsibility would fall solely on Chair Jaime Harrison; a powerful panel within the DNC, such as the Rules and Bylaws Committee; or all 448 voting members of the party body.

Withdrawing at that late date would also make ballot access considerably harder since many states restrict presidential candidates from withdrawing after accepting the nomination. In Wisconsin, for example, a presidential nominee can only withdraw from the ballot in case of death.

The conservative Heritage Foundation’s Oversight Project issued a memorandum in April outlining the potential legal hurdles to ballot access that would face a Democratic nominee in the event of Biden’s withdrawal.

“This isn’t as easy as ‘abracadabra,’” Mike Howell, executive director of Heritage’s Oversight Project, said in a Friday call with reporters.“There is going to be a lot of litigation.”

Howell and other Heritage attorneys maintain that there could be legal challenges to a new candidate even if they are nominated in lieu of Biden at the convention.

But a Democratic elections attorney told HuffPost that ballot access is mainly only an issue after the formal acceptance of the party nomination.

Party officials are unlikely to allow Biden to be nominated at the convention only to have him withdraw later on, save for a reason related to his health, according to Noel.

Then again, in the absence of a consensus choice to replace Biden, Noel also suspects party elders will decide against pressuring Biden to withdraw altogether.

“There are so many people who not just want the job, but to whom Democrats want to give it, that it’s really messy,” he said. “The party is risk-averse, and I think that’s how they’re going to behave.”