US Vice President Kamala Harris has received the support of enough Democratic delegates to win her party's presidential nomination, CNN and other US media reported late on Monday.

Harris will need the support of at least 1,976 pledged delegates out of nearly 4,000 in order to decisively secure the Democratic presidential nomination during an official vote in the coming weeks, a number which US outlets reported she has now surpassed.

Still, the Democratic Party plans to push forward with a virtual roll call in which delegates to its convention can choose a presidential nominee before they gather next month in Chicago — despite Harris being overwhelmingly favoured to replace US President Joe Biden at the top of the ticket.

The convention rules committee will meet Wednesday to approve how the virtual roll call will work.

It does not list a date for when virtual voting would begin, but Democratic National Committee Chair Jaime Harrison said the process will be completed by August 7 — or 12 days before the party's convention begins.

“We are living through an unprecedented moment in history and, as a party, we are tackling it with the seriousness that it deserves,” Harrison said on a conference call with reporters.

"We are prepared to undertake a transparent, swift and orderly process to move forward as a united Democratic Party with a nominee who represents our values.”

He also said Democrats "can, and will, be both fast and fair as we execute this nomination.”

Biden dropped out of the presidential race on Sunday, ending weeks of fighting among Democrats, many of whom feared he was not up to the rigours the campaign — much less a second term — following his poor debate against Repulican nominee Donald Trump last month. (Agencies)