US Vice President Kamala Harris says she is proud and grateful to have secured enough support from Democratic National Convention delegates to become the nominee for president.

President Joe Biden threw his support behind Harris on Sunday when he withdrew from the race amid questions about his age and health.

He has pledged to remain in office as president until his term ends on January 20, 2025.

An Associated Press survey of delegates on Monday showed Harris had the support of 2538 delegates, well beyond the 1976 needed to win the delegates’ vote in the coming weeks.

“When I announced my campaign for president, I said I intended to go out and earn this nomination,” Harris said in a statement on X.

“Tonight I am proud to have secured the broader support needed to become our party’s nominee, and as a daughter of California, I am proud that my home state’s delegation helped put our campaign over the top. I look forward to formally accepting the nomination soon.”

Democratic National Committee chairman Jaime Harrison said on Monday (local time) the party will deliver a presidential nominee by August 7.

Delegates could still change their minds before August 7, but nobody else received any votes in the AP survey, and 57 delegates said they were undecided.

“I am grateful to President Biden and everyone in the Democratic Party who has already put their faith in me, and I look forward to taking our case directly to the American people,” Harris said.

Statement from Vice President Kamala Harris on becoming the presumptive Democratic nominee for President pic.twitter.com/2vp84d5Bie

— Kamala HQ (@KamalaHQ) July 23, 2024

Harris has also become the funding focus of Democrat donors, raising almost $US50 million ($75.1 million) in just over 24 hours since declaring her run – much of it from smaller donors.

Earlier, in her first public appearance since Biden’s announcement, Harris rallied supporters on Monday with a debut campaign speech vowing to go after Republican nominee Donald Trump like the courtroom prosecutor she once was.

“I took on perpetrators of all kinds. Predators who abused women, fraudsters who ripped off consumers, cheaters who broke the rules for their own gain,” Harris told campaign workers 28 hours after 81-year-old Biden abandoned the 2024 White House race and endorsed her.

“Hear me when I say I know Donald Trump’s type. In this campaign, I will proudly put my record against his,” said Harris, who was attorney-general of California and a US senator before serving as Biden’s vice president.

The Trump campaign responded to Harris’ comments. “Kamala Harris is just as incompetent as Joe Biden and even more liberal,” national press secretary Karoline Leavitt said.

“Not only does Kamala need to defend her support of Joe Biden’s failed agenda over the past four years, she also needs to answer for her own terrible weak-on-crime record in California.”

Trump is due to be sentenced in September after having been found guilty of falsifying business records to hide hush money payments to a porn star.

He also faces criminal charges related to his efforts to overturn Biden’s 2020 victory. He falsely claims he lost in 2020 because of election fraud.

Harris, 59, outlined a series of policies she promised to pursue including signing laws to protect abortion rights and ban assault rifles and said she would make rebuilding the middle class the focus of her presidency.

Biden’s departure was the latest shock to a White House race that included his disastrous June 27 debate performance against former president Trump and the July 13 near-assassination of Trump by a gunman during a campaign stop.

Harris, who is Black and Asian-American, would fashion an entirely new dynamic with Trump, 78, offering a vivid generational and cultural contrast.

The Trump campaign has been preparing for her possible rise for weeks, sources told Reuters.

It sent out a detailed critique of her record on immigration and other issues on Monday, accusing her of being more liberal than Biden.

-with AAP