A growing number of senior Democrats are backing Kamala Harris to be the party's presidential candidate, after Joe Biden quit the race.
Her supporters include Gavin Newsom and Pete Buttigieg, who themselves were touted as possible nominees.
President Biden withdrew from November's election on Sunday, saying in a statement it's "in the best interest of my party and the country".
Biden, 81, had faced increasing calls to step aside since last month's TV debate against Donald Trump.
He has endorsed Harris, who says she intends to "earn and win" the nomination.
Biden will remain as president - but the Republican nominee, Donald Trump, says "if he can't run for office, he can't run our country".
