Biden campaign says it has raised more than $34 million since Harris joined the ticket

The haul was raised between Tuesday, the day they announced Harris would be Biden's running mate, and Wednesday, the day the two appeared together in public for the first time.

"Team Biden-Harris Digital raised $34.2 million between the 11th and 12th," the campaign's digital director, Rob Flaherty, announced on Twitter. He said this includes $1.3 million raised on yard signs alone.

A Biden campaign aide tells CNN that their biggest fundraising hour of the campaign came during their first event on Wednesday -- from 5 p.m. to 6 p.m., ET -- when they raised more than $3 million in online-only donations.

On Wednesday night, Biden expressed gratitude to donors.

"The response has been overwhelming. In the last 24 hours, we've raised $26 million. One hundred and fifty thousand of you (were) first-time contributors," Biden said at a virtual grassroots fundraiser. "It's really palpable, the excitement, because there's so much at stake."

After his announcement, the campaign raised an additional $9.6 million.

The announcement came just hours after Biden and Harris appeared together for the first time as running mates and a day after the former vice president named Harris, a senator from California and former presidential candidate, as his vice presidential pick. While the remarks were delivered without the typical large crowd due to Covid-19 restrictions, the launch event was carried live by the six biggest networks: ABC, NBC, CBS, along with FOX, CNN and MSNBC.

The spike in donations could potentially help the two Democratic candidates eventually match or beat the August fundraising haul of President Donald Trump and the Republican National Committee. CNN reported last week that Trump's campaign and the RNC had bested Biden and the Democratic National Committee's fundraising haul in July, but the money gap between the two camps has essentially closed.

Trump's campaign and the RNC announced last week that their joint fundraising committees had raised more than $165 million in July. That bests Biden and the DNC's haul of $140 million last month.

However, Biden and the DNC ended July with $294 million on hand, the former vice president's campaign said last Wednesday. That's just $6 million less than the more than $300 million that Trump and the RNC reported having on hand.

This story has been updated to reflect updated fundraising numbers.