The July figure – more than double the US$138.7 million raised by Republican rival Donald Trump in the same month – brings the total money raised by Harris and Biden before her to more than US$1 billion, the fastest a presidential campaign has crossed that threshold in history, the campaign said.

July was set to be a disappointing month for Democrats as big-dollar donors withheld money in an effort to force Biden out of the race, but Harris’s emergence as the party’s presidential candidate energized voters and donors.

More than US$200 million of the US$310 million came in the first week following Biden’s endorsement of Harris, the campaign said.

Two-thirds of the July donations came from first-time donors and 94% of the donations were US$200 or less, the campaign said.

“This is a history-making haul for a candidate who will make history this November. The tremendous outpouring of support we’ve seen in just a short time makes clear the Harris coalition is mobilised, growing, and ready to put in the work to defeat Trump this November,” said Harris for President campaign manager Julie Chavez Rodriguez.

The Harris campaign had US$377 million in cash on hand at the end of the month, US$50 million more than the Trump campaign’s US$327 million.

Trump’s fundraising for July was 24% higher than the US$111.8 million that the campaign said it raised in June.

The assassination attempt against Trump on July 13 at a rally in Butler, Pennsylvania was expected to spur campaign contributions to the former president. Trump’s fundraising had previously surged when he was convicted in late May on felony charges related to a hush-money payment to a porn star ahead of the 2016 election.

Polls showed that Trump had built a lead over Biden, including in battleground states, after Biden’s disastrous debate performance on June 27, but Harris’s entry to the race changed the dynamic with recent polls showing a tight contest.