Vice President Kamala Harris secured sufficient delegate support on Monday to become the Democrat's official presidential candidate, after receiving endorsements from leading contenders for the position and prominent political officials, including House Speaker Nancy Pelosi, an Associated Press survey showed.

However, delegates remain free to vote for any candidate at the August Democratic National Convention DNC or during a potential virtual Democrat roll call before the event in Chicago.

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Following President Joe Biden's announcement last Sunday of his withdrawal from the 2024 presidential race against Donald Trump, he endorsed Harris as his successor.

Just hours before the delegate vote, Democratic fundraiser ActBlue disclosed that Harris had raised $81 million in the first 24 hours of her campaign, setting a record for the largest single-day fundraising total by a presidential candidate in history.

AP's count showed that Harris passed 1,976 delegates. While this does not make her the party's official nominee, this support count shows she has most likely already landed the spot.

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All 50 Democratic Party state leaders have expressed their support for Harris to become the Democrat's presidential nominee, Reuters reported on Monday citing informed sources.

Participants declared their "full support" to the vice president, one source said.

Axios had reported earlier that Biden's decision to run for re-election was initially clouded by concerns over Harris' readiness to face former Trump.

The chief reasons include concerns about her leadership effectiveness, high staff turnover, and her difficulties in handling politically risky situations, the news site said citing three aides familiar with the discussions.