Now that President Joe Biden has decided to drop out of this November's presidential election, the future of who will be on the Democratic ticket, and how the nominee will be selected, remains in question.
President Biden has offered his endorsement of Vice President Kamala Harris, which would seemingly make her the odds-on favorite to become the Democratic nominee. But as of Sunday afternoon, it's too early to say whether anyone will challenge her for the nomination.
There is little precedence for President Biden's decision to drop out.
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Here is what is known about the process.
How the nomination process works
President Biden only faced little opposition in this year's presidential primaries — winning nearly all of the possible 3,934 delegates for this year's convention. He only needed 1,968 delegates to secure the nomination.
Now, those 3,934 delegates will have an important decision to make — whether to support Harris or a potential challenger.
Prior to 1972, most delegates were not picked in presidential primaries, meaning political conventions were not merely the ceremonial events they have largely become. The party opted to rely more on primaries after a chaotic 1968 convention that involved violent clashes between campaigns and delegates.
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Before dropping out of the race, Scripps News' Haley Bull asked the president whether delegates were free to vote for other candidates.
"Obviously they're free to do whatever they want," he said.
But officially, President Biden would have needed to submit a letter to the party to release those delegates. Before Sunday, no known letter was sent.
Now that those delegates are released, there remain questions of when they'll vote for a new nominee. The Democratic National Convention is scheduled to begin on Aug. 19, but Democratic leaders said prior to Sunday that they plan to convene delegates virtually beforehand. They cite an Ohio law that requires presidential nominations to be determined 90 days before the presidential election.
However, the Ohio legislature voted in late May to extend the deadline, which would afford Democrats the opportunity to choose their nominee in person if the party chooses.
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Now that Biden has dropped out, his delegates are free to vote for potential replacements. It will still take 1,968 delegates for a candidate to become a nominee. If a nominee does not reach a majority of the 3,934 delegates during the first round of voting, a group of 700 "superdelegates" will join, which would raise the number needed to secure the nomination. These superdelegates consist of top political officials within the party, including members of Congress and state governors.
Could Democrats go to Chicago next month without a nominee decided? Democratic National Committee Chair Jamie Harrison did not have immediate clarity on Sunday about the next steps.
“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," Harrison said. "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."
What happens to campaign dollars
This will become a key question no matter how the nomination is decided. Because Harris was Biden's running mate, she would presumably have access to the same campaign staff, offices, and yes, money.
There is no clear answer on how much of the campaign apparatus can be transferred to Harris, and her potential running mate, assuming she becomes the Democratic nominee.
And if Democrats choose a challenger and not Harris, that candidate would likely have to launch an entirely new campaign apparatus, like hiring a staff and opening officers, in short order.
If Harris becomes the nominee, who becomes her running mate?
Within hours of President Biden's announcement, numerous prominent Democrats released statements expressing support for Harris. Among them were Sen. Tim Kaine, who ran for vice president in 2016, former Secretary of State Hillary Clinton, Sen. Elizabeth Warren, and California Gov. Gavin Newsom.
While many have seen Newsom as a potential presidential candidate, he would likely be unable to serve as Harris' running mate given that the constitution requires the presidential and vice presidential candidates to reside in different states.
But some prominent Democrats, who might have been seen as ones with potential presidential or vice presidential aspirations of their own, did not offer immediate endorsements. Among them were Kentucky Gov. Andy Beshear, Transportation Secretary Pete Buttigieg, Pennsylvania Gov. Josh Shapiro, and North Carolina Gov. Roy Cooper.
Once a presidential nominee is chosen, delegates will be tasked to vote on whether to accept the Democratic nominee's choice of running mate.
What happens to Biden?
President Biden has given no indication he plans to step down before his term ends on Jan. 20. At this point, he'll become the first sitting president since Lyndon B. Johnson in 1968 to not seek reelection while remaining eligible for another term.
"I believe it is in the best interest of my party and the country for me to stand down and to focus solely on fulfilling my duties as President for the remainder of my term," President Biden wrote. Biden's term expires on Jan. 20, 2025.
Some Republicans have suggested that if President Biden won't run for reelection, he also shouldn't be able to finish his term.
"Biden must step down from office immediately," House Speaker Mike Johnson wrote in a statement.
Some lawmakers have even suggested that the 25th Amendment be evoked. The 25th Amendment outlines the steps for when a president leaves office.
Section 4 in the 25th Amendment specifically gives the vice president and a majority of either the cabinet or Congress the ability to remove the president from power when the president " is unable to discharge the powers and duties of his office."
"If Joe Biden is unfit to run for re-election, he is unfit to carry out his term. 25th Amendment," wrote Oklahoma Sen. Markwayne Mullin on X.