Many Democrats on Sunday quickly backed Vice President Kamala Harris to run as the party's presidential nominee against Donald Trump after incumbent President Joe Biden's abrupt departure from the race, but some powerful party members, including former House of Representatives speaker Nancy Pelosi, stayed quiet.

After weeks of in-party fighting between Democrats on whether Biden, 81, should stay in the race, a rush of support coalescing behind her is crucial just over 100 days before November's election. However, there are plenty of doubts inside the Democratic Party about whether Harris can beat Trump in November.

Biden himself endorsed Harris on Sunday, not in his initial letter stepping down, but in a separate statement. He was quickly followed by the powerful Congressional Black Caucus, several key donors, lawmakers including US Senator Patty Murray, and super PACs including Priorities USA and Unite the Country.

"Today I want to offer my full support and endorsement for Kamala to be the nominee of our party this year," Biden said on social media platform X. "Democrats – it's time to come together and beat Trump. Let’s do this."

Dmitri Mehlhorn, an adviser to Reid Hoffman, the LinkedIn founder and a major Democratic donor, called Harris "the American dream personified," noting she was the daughter of immigrants. "She is also toughness personified, rising from my hometown of Oakland, California, to become the top prosecutor of the state. With Scranton Joe stepping back, I cannot wait to help elect President Harris."

Still, others including Pelosi thanked Biden for his patriotism but did not yet throw their support behind Harris or any other candidate.

US Senator Peter Welch, the first Democratic senator to call on Biden to drop his re-election run, called for an open process to nominate Harris.

The Democrats should have “an open process so that whoever our nominee is, including Kamala, has the strength of having a process that shows the consensus position of the party,” he said. “The debate in the Democratic Party is who can carry on the legacy of President Biden and defeat Trump.” (Reuters)