WASHINGTON

When US President Joe Biden abruptly announced Sunday afternoon that he would be ending his bid to secure a second term in office, many were caught flat-footed.

That included not only many voters around the nation, but White House staffers, senior Democrats and the Democratic National Committee, all of whom are now in what Biden's former boss, ex-President Barack Obama, described as "uncharted waters."

Biden had long been unwavering in his determination to challenge Republican presidential nominee and former President Donald Trump in November despite mounting Democratic calls for him to step aside after he badly flubbed a high-stakes debate with Trump in June. The performance heightened already significant concerns about Biden's mental acumen and his ability to defeat Trump at the ballot box as many Democrats consider this year's election a make-or-break contest for the soul of American democracy.

Even as the chorus grew, Biden's insistence that he would be the party's nominee was echoed by many in his inner circle who continued to insist in the days and even minutes running up to his surprise announcement that Biden would be the party's nominee.

Andy Bates, a senior spokesperson in the president's press shop, denied a report Friday that Biden's family was discussing a potential end to the re-election campaign. "Wrong. Keep the faith," Bates said on X in response to the NBC News article.

That sentiment continued to be run publicly by many senior Democrats and the Biden campaign, which just 45 minutes before the president posted a note to X announcing that he would be stepping aside solicited campaign donations from Democrats.

Endorsement of Kamala Harris does not cement her role as Democratic nominee

In announcing his decision to end his re-election bid, Biden threw his weight behind Vice President Kamala Harris, offering her his "full support and endorsement" ahead of next month's nominating convention.

That does not make her the Democratic nominee, however.

The party's blessing will only come with the support of the majority of Democratic delegates during the Aug. 19-22 Democratic National Convention (DNC), and it is unclear who will be competing for the nomination outside of Harris, much less when and how candidates will seek to garner delegates' support.

Committee Chair Jaime Harrison has maintained that there is no automatic successor to Biden, emphasizing that the party would pursue what he described as an "orderly process" to select a nominee.

"The work that we must do now, while unprecedented, is clear. In the coming days, the Party will undertake a transparent and orderly process to move forward as a united Democratic Party with a candidate who can defeat Donald Trump in November. This process will be governed by established rules and procedures of the Party. Our delegates are prepared to take seriously their responsibility in swiftly delivering a candidate to the American people," Harrison said in a statement.

"In short order, the American people will hear from the Democratic Party on next steps and the path forward for the nomination process," he added.

Those "next steps" remain a mystery to many, not least of which are senior DNC officials, who are all in the same boat with just four weeks until the convention begins.

While it is possible that individual delegates will cast their ballots in Chicago during what would be known as an open convention, the prospect has been raised that the decision could be made well before that during a previously floated virtual roll call to meet Ohio's ballot eligibility requirements.

The party had planned as recently as Friday to nominate Biden virtually at some point between Aug. 1-7 in order to ensure that the Democratic nominee met a key deadline and was on Ohio's ballot. It is unclear if Democrats will attempt to choose their nominee via a virtual vote to ensure they conform to a deadline whose standing is now unclear for several reasons, or if the matter will be deferred for an open convention that is not slated to begin until more than a week and a half later.

A convention is considered "open" when no candidate has the majority of the delegates' support. That has not happened in decades.

All of the delegates that Biden secured during the Democratic primary are now free to throw their support behind a candidate of their choosing. While the president may have sought to influence many with his endorsement of Harris, they are not obligated to support her.

A later open convention would allow prospective candidates a bit more time to court delegates ahead of the convention. Amid the uncertainty, all eyes are slated to be fixed on this week's expected meeting of the DNC's rules committee.

Democrats face wild field for potential nominee with just 4 weeks until convention

California Gov. Gavin Newsom, thought to be one of the leading Democrats for the nomination, dismissed any speculation that he would compete for the role, announcing his endorsement of Harris on Sunday night.

"With our democracy at stake and our future on the line, no one is better to prosecute the case against Donald Trump's dark vision and guide our country in a healthier direction than America’s Vice President, @KamalaHarris," Newsom wrote on X.

Other top-tier potential candidates have kept their cards close to their chest, not indicating one way or another how they will proceed.

That includes billionaire Illinois Gov. JB Pritzker, Michigan Gov. Gretchen Whitmer, Pennsylvania Gov. Josh Shapiro, West Virginia Sen. Joe Manchin, and California Representative Ro Khanna.

Whoever wins the nomination will need the support of the majority of the Democrats' roughly 3,900 pledged delegates. An additional group of about 700 superdelegates do not participate in a first roll call vote.

They can take part in later rounds of balloting if no candidate secures a majority on the first vote. A lack of a clear nominee after a first-round vote would set up what would be known as a brokered convention, allowing the superdelegates to take part in successive balloting until one candidate emerges with a clear majority.