Barack Obama helped raise $11 million for White House hopeful Joe Biden during a Tuesday virtual fundraiser where the former president said a "great awakening" among Americans could help defeat Donald Trump in November's election.

The two-term Democrat proved a major draw, bringing in a substantial audience and raising over $11 million in total, making it the most successful finance event of the entire campaign, according to Biden press secretary TJ Ducklo.

Some $7.6 million of that came from 175,000 grassroots donors "who continue to power this campaign every single day," Ducklo tweeted.

Obama's split-screen appearance with the Democratic presidential candidate was his first with Biden since he endorsed his former vice president in mid-April.

"I am here to say the help is on the way if we do the work, because there's nobody I trust more to be able to heal this country and get back on track than my dear friend Joe Biden," said Obama.

"What makes me optimistic is the fact that there is a great awakening going on around the country, particularly among younger people" who are "fed up with the shambolic, disorganized, mean-spirited approach to governance that we've seen over the last couple of years," he added.

Biden said he agreed with Obama's remarks on political change. He also suggested world leaders have grown weary of Trump, saying "they're desperately, desperately waiting for American leadership."

Biden has held no in-person campaign rallies since mid-March due to the coronavirus pandemic.

He has largely remained in his Delaware home, using social media, television interviews or advertisements to attack Trump for what he says is an inadequate, failed effort to contain the virus's spread or improve economic conditions for millions of suffering Americans.

Trump, meanwhile, has disregarded his own government's guidelines and held several in-person events, including a weekend rally in Tulsa, Oklahoma.

The president followed up with a Tuesday rally in Phoenix. Both locations are experiencing spikes in new coronavirus cases, but most attendees did not wear masks.

Biden's online event confirmed the continued popularity of the nation's first black president, and the campaign said it "highlights the power of the grassroots movement" as it launches a more intense spirit of campaigning.

Obama spoke of the urgency of advocating for broader systemic change during a period of heightened tensions over racial injustice and police brutality.

"Whatever you have done so far isn't enough," Obama told listeners, urging them to use the momentum of recent coast-to-coast street protests as a catalyst for political change.

"We have this unique chance to translate growing awareness of injustice in society into actual legislation and institutional change," Obama said.

In May, Biden and the Democratic Party raised nearly $81 million, 10 percent more than Trump, although the president has more overall campaign cash.