The president's party is now scrambling to nominate a new ticket with just weeks until the Democratic National Convention.
Estella and Doug Kessler of Selma are delegates who had pledged their support to Biden.
"We knew who our candidate was going to be. And then it all changed," she said. "He's chosen to do something different, and I will support Kamala Harris."
Fresno Democratic delegate Eric Payne says work is already underway to nominate Harris.
"The war chest, now instead of it being Biden-Harris, is now Harris," Payne said. "The campaign committee has already gone over and made the changes."
The work to nominate Harris is facing pushback, however. California Republican National Committeewoman Harmeet Dhillon says Democratic voters did not choose Harris at the primary polls.
"This is a very abrupt turnaround," Dhillon said. "Over 15 million Democrats have voted in primaries throughout which they were assured Joe Biden would be the nominee of the party."
Payne and the Kesslers, along with California's nearly 500 Democratic delegates, will play an important role at the convention in Chicago next month.
The party has a tough choice: Support Vice President Kamala Harris' bid or face a floor fight, a process that would play out in front of the cameras.
"I think any political angst will be ironed out before convention," Payne said.
As more Democrats throw their support behind Harris, Action News has learned party meetings are underway, and a nomination could be just days away.
"I think it will be virtually done in the next couple (of) days," Doug said. "And then it will be reconfirmed when we're in Chicago."
California Republicans say they are ready to face off against the Vice President.
"If I were Democrats, I would certainly be nominating someone other than the very unpopular Kamala Harris," Dhillon said.
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