Harris' campaign announced on August 2 that it had raised $310 million in July, thanks to small donations from voters.

This figure is more than twice as high as Republican rival Donald Trump, at $138.7 million, earned in the same month.

According to Ms. Harris’s campaign, the total amount of money she and President Joe Biden raised before he dropped out of the race for the White House had reached $1 billion, the fastest presidential campaign in history to reach that milestone.

Democrats were initially expected to raise little money in July as big donors pressured Biden after his dismal debate performance in June. But after Biden dropped out and endorsed Harris, the picture changed dramatically.

Ms Harris's campaign said she "sucked in" more than $200 million in the first week after Mr Biden dropped out.

Two-thirds of Harris's July donations came from first-time donors, and 94% of those donations were small, $200 or less.

"The overwhelming support we've seen in just a short period of time makes it clear that Harris is ready to fight to defeat Trump this November," said Harris campaign manager Julie Chavez Rodriguez.