(NewsNation) — Responding to calls from a growing number of Democratic lawmakers to drop his re-election bid, President Joe Biden announced Sunday that he will not seek reelection in November against former President Donald Trump.

The Democratic National Convention is one month away and Biden’s withdrawal now sets off a chaotic few weeks as Democrats decide how best to move forward.

Here’s what that process could look like:

How would replacing Biden work?

Since Biden willingly stepped aside before the party formally nominated him, his 3,896 pledged delegates are free to vote for whomever they choose at the convention.

However, Biden has thrown his weight behind Vice President Kamala Harris, which effectively amounts to a dare to those delegates, and the party as a whole, not to place her at the top of the ticket.

Still, there are plenty of Harris skeptics, and while she has already secured endorsements across the party, big names like former President Barack Obama and former Speaker Nancy Pelosi have not endorsed her as of Monday morning.

It leaves the possibility of an open convention in place. Democrats could host a mini-primary before the convention which would likely mean a campaign blitz between potential replacements, complete with town halls, speeches and debates.

Rep. Dean Phillips, who was the only Democrat to formally challenge Biden in this year’s primary elections, has called for an open convention. Author Marianne Williamson, who resumed her presidential campaign after the June debate between Biden and Trump, is the only candidate besides Harris as of Monday morning.

Sen. Joe Manchin, I-W.V., inquired about running but was told only registered Democrats are eligible for the party’s nomination.

How would the running mate be decided?

If Vice President Kamala Harris or someone else were to become the nominee, they would choose their running mate, not the party. However, whoever they select would still need to win the delegates’ support.

Harris is the most obvious successor should Biden withdraw, but it’s not clear who would join her on the ticket.

Potential options include a host of popular Democratic governors including Kentucky Gov. Andy Beshear, Pennsylvania Gov. Josh Shapiro, Illinois Gov. JB Pritzker, Michigan Gov. Gretchen Whitmer or California Gov. Gavin Newsom.

Those state leaders could also launch bids of their own if they choose to.

What’s the timeline?

The Democratic National Convention opens in Chicago on Aug. 19. That event is typically when the party formalizes its nominee but this year is set to look different.

Democrats were planning to officially nominate Biden during a “virtual roll call” before the convention in order to work around Ohio’s filing deadline which was Aug. 7 but was later extended to Aug. 31.

With Biden out of the race, it’s unclear if that virtual nominating process will continue, or if the Democrats will wait until August to formally nominate Harris or someone else.

What would happen to the Biden-Harris campaign money?

There’s some uncertainty about what would happen to the Biden campaign’s $91 million in the bank if he were to drop out of the race. It may depend on who his replacement is.

If the candidate is Harris, or she becomes someone else’s running mate, then the new ticket would maintain access to the funds, Saurav Ghosh, a lawyer at the Campaign Legal Center, told Reuters.

However, that transition could face legal challenges, especially if Biden drops out before he’s formally nominated.

If neither Biden nor Harris appear on the ticket, the campaign would have to give almost all of the money back, Kenneth Gross, senior political law counsel at Akin Gump, told the Associated Press.

At that point, the Biden-Harris campaign could designate the funds for a super PAC or the party itself. If that happened, it would come at a cost, in part, because television advertising rates are higher for parties than for candidates.

The Associated Press contributed to this report.