President Biden is facing increasing pressure from Democratic leaders to reconsider his reelection bid. Top Democrats have met with him in recent days to convey one message: His continued candidacy is hurting the Democratic Party’s ability to control either chamber of Congress next year. Former president Barack Obama has separately told allies that Biden’s own path to victory has greatly diminished.

But Biden and his campaign advisers have remained defiant, insisting that he will not drop out of the race. Biden tested positive for the coronavirus on Wednesday and is quarantining in his vacation home in Rehoboth Beach, Del.

If Biden were to make the extraordinary decision to withdraw from the race, the coming days will prove pivotal as Democratic leaders try to unite the party’s many factions around a new standard-bearer. Here are some details on how the process could unfold.

Who would replace Biden?

Vice President Harris is the likeliest candidate to replace Biden at the top of the ticket, and many in the party have already signaled they’d accept her as the nominee. And at a NATO news conference on July 11, Biden said he wouldn’t have picked her as his vice president “unless I thought she was qualified to be president from the very beginning.”

But Harris’s nomination isn’t guaranteed just because she’s Biden’s vice president and running mate. The Democratic Party is free to tap a different replacement – a governor, perhaps – if its members coalesce around another candidate. Even then, the nominee won’t become official until delegates vote.

How would a new nominee be chosen?

Unlike a president’s resignation, which automatically promotes the vice president, Biden dropping out of the race does not mean Harris will be at the top of the ticket. Most Democrats and strategists expect that she is the most likely replacement, but delegates who select the presidential nominee at the DNC are free to vote for any candidate they like.

If Democrats fail to coalesce behind someone, it sets up the potential for an open convention, which the party hasn’t had since 1968. Then there would be tremendous political jockeying behind the scenes as would-be nominees seek support from individual delegates. However, Democrats would probably try to avoid this by attempting to solidify support behind one person before the convention, and many delegates, if not most, would be likely to back the party’s preferred candidate.

How quickly could a nominee be chosen?

Even if Biden and the party endorse a replacement, no one becomes the official nominee until delegates vote. The Democratic National Committee has signaled plans to hold a virtual roll call that could begin the first week of August to nominate its presidential ticket. If it cancels that plan, then the nominee will be chosen at the convention, which is scheduled to begin on Aug. 19.

How well does Harris poll against Trump?

Even though Harris is widely thought of as Biden’s top possible replacement, recent polls find little difference between how she and Biden stack up against Donald Trump.

In a Washington Post average of 11 post-debate polls, Trump edged out Biden by 1.9 percentage points on average, which is similar to Trump’s 1.5-point edge over Harris in these surveys. Four polls showed Harris polling slightly better than Biden, four slightly worse and three showed no difference.

A Washington Post-ABC News-Ipsos poll this month found 44 percent of Americans overall saying they would be “satisfied” if Biden stepped aside and Harris became the Democratic nominee, including 70 percent of Democrats and Democratic-leaning independents.

In that same poll, 29 percent of Democrats and Democratic-leaning inpendents volunteered Harris as their choice for the party’s nomination if Biden steps aside, while 7 percent mentioned California Gov. Gavin Newsom (D), 4 percent named former first lady Michelle Obama and 3 percent each named Transportation Secretary Pete Buttigieg and Michigan Gov. Gretchen Whitmer (D). Half of Democrats didn’t name anyone.

What would happen to the money Biden raised?

If Biden withdraws from the race, the dollars in his campaign account are considered “excess campaign funds” that can be contributed to the Democratic National Committee or to an independent expenditure committee. But if he withdraws before he is the official nominee of the party, he could face limits in donating to other candidates.

Some Democratic lawyers and operatives, who spoke on the condition of anonymity to discuss internal discussions, argue that because Kamala Harris’s name is on the paperwork filed with the Federal Election Commission to set up the committee, Biden could hand control of the account to Harris if he were to step aside. But several Republican campaign finance lawyers noted that that legal theory has not been tested. Prominent Republican lawyer Charlie Spies recently argued in the Wall Street Journal that both Biden and Harris would have to be officially nominated by their party before a handoff of the account could occur.

If the Democratic Party chooses a nominee who is someone other than Harris, the Biden campaign could still transfer its funds to the DNC or a super PAC that intends to back the new ticket.

What would this mean for the DNC convention?

That largely depends on whether the party has coalesced around one candidate and no one else has decided to challenge that person for the nomination. In that situation, the delegates would be likely to vote for the party’s chosen candidate at the convention, as they would have done for Biden. If however, there are multiple candidates seeking the nomination, then there would be an open convention. Delegates would be free to vote for their candidate of choice. In the first round of voting, only pledged delegates – around 3,900 – can vote. If no candidate reaches a majority, then superdelegates – around 700 party leaders and elected officials – can vote on subsequent rounds until a nominee is chosen.