DNC commits to "transparent and orderly process" to determine new nominee

• Biden's bombshell announcement — less than a month before the Democratic National Committee — begins an unprecedented, chaotic process to determine who will lead the ticket.

State of play: Harris has a huge edge over any other Democrat, further vaulted by Biden's endorsement, which has already triggered a flood of endorsements from other party heavyweights.

• Delegates, the vast majority of which had already been pledged to Biden, will now vote on the party's nominee, either at a virtual roll call or on the floor of the convention next month. They are not obligated to back Biden's choice for the Democratic nomination.

What to watch: The DNC had been scrambling to proceed with a "virtual roll call" in early August, which would have solidified Biden as the nominee before the convention, Axios' Hans Nichols and Alex Thompson reported.

• It's not clear whether the DNC will proceed with plans to try for a virtual convention.

What they're saying: "This process will be governed by established rules and procedures of the Party," Harrison said in the statement on Sunday.

• "Our delegates are prepared to take seriously their responsibility in swiftly delivering a candidate to the American people."

Zoom in: Some prominent Democrats — including former President Obama, Senate Majority Leader Chuck Schumer (D-N.Y.) and House Minority Leader Hakeem Jeffries (D-N.Y.) — issued statements on Biden's exit Sunday that didn't mention Harris.

• Former Speaker Nancy Pelosi (D-Calif.), still one of the party's most influential figures, also didn't mention Harris.
• That doesn't mean they won't ultimately rally behind her.

Go deeper Biden endorses Kamala Harris: What to know about her presidential bid