It would be the first US presidential election rematch in nearly 70 years.
Biden became the presumptive nominee of his party when he won a sufficient number of delegates in Georgia.
That pushed Biden's count past the 1,968 needed to win a majority of the delegates to the Democratic National Convention in Chicago in August. That's where his nomination will be made official.
Trump is also the presumptive nominee
Former President Donald Trump, who won the Republican primaries in Georgia, Mississippi, and Washington state, also clinched the Republican nomination.
He won at least 126 of their combined available delegates, surpassing the 1,215 needed to become presumptive nominee.
Trump's last Republican primary rival, Nikki Haley, the former United Nations ambassador and governor of South Carolina, dropped out of the race last week.
In the United States, a presidential candidate does not officially become the Republican or Democratic nominee until he or she wins the convention vote.
