Less than a week after Vice President Kamala Harris launched her presidential campaign in the wake of President Joe Biden's withdrawal from the race, supporters are hitting the ground running -- and gathering online in video calls, with some claiming record-breaking turnout and massive fundraising hauls.

A few even boast celebrity backing -- with well-known stars calling on attendees to support Harris' presidential run. The calls were organized across a diverse swath of Harris' supporters, including Indian Americans, members of the LGBTQ+ community, the Latino community and women. Organizers have indicated the calls have raised millions for Harris' campaign.

Much of the momentum came from a Sunday night call led by Win With Black Women advocacy group founder Jotaka Eaddy that drew tens of thousands of attendees, raised more than $2 million for the just-launched Harris campaign and inspired a similar call led by Black men the next night that the group said raised $1.3 million more for Harris' campaign.

"The journey to reclaim our democracy and advance our shared values begins now, with unwavering determination and a unified vision. Unity among not only Black women, but all Americans is not just vital to the state of our democracy but necessary to propel our nation forward," Eaddy said on the call.

On Thursday night, a Zoom call featured two-time Women's World Cup soccer champion, former Olympian and LGBTQ+ advocate Megan Rapinoe. She joined an "Answer the Call 2024" Zoom webinar that organizers said was meant to follow the Win With Black Women call's blueprint and to galvanize white women in support of Harris on Thursday night.

The athlete called on other white women to follow in the footsteps of the Black women organizers.

"White women, this is our opportunity to show up not only for ourselves, but for Black women," Rapinoe said.

"They've given us the whole playbook on how to show up and energize and be organized, and really do the right thing and tap into all of our networks. So let's just follow their lead," she added.

Rapinoe also called on attendees to organize and vote, acknowledging the women who fought for suffrage throughout history.

Organizers of that call -- which also featured pop singer P!NK and actresses Connie Britton and Katie McGrath -- have said that they raised more than $8 million and had more than 160,000 participants, which they claimed broke records for attendees on a single Zoom video call. (ABC News has reached out to Zoom to confirm, although Zoom often cannot share details about specific calls, which are kept encrypted.)

The previous day, several organizers and leaders of South Asian descent from across the country held a "South Asian Women for Harris" Zoom video call on Wednesday launching their first event since Harris announced her run for president. Harris, if elected, would be the first U.S. president of South Asian descent.

Organizers said the call, which had about 9,000 people in attendance, raised more than $260,000. It featured appearances by Washington Rep. Pramila Jayapal and actress and comedian Mindy Kaling. Kaling appeared alongside Harris in a video during Harris' 2020 cycle presidential run, where they cooked Masala dosas with each other.

"Culturally I was raised to keep my head down and to not make a stir," Kaling told participants. "I don't know if people can relate to that, but that is the opposite of what Kamala Harris has done with her life, and I love her for that. And because of that strength in her, she's going to become the next president and make some serious changes."

A call with Latina leaders on Wednesday, meanwhile, featured Hollywood actresses Rosario Dawson and Rosie Perez, New Mexico Gov. Michelle Lujan Grisham, and New York Rep. Nydia Velázquez. Organizers said they raised more than $110,000 and registered more than 400 new volunteers.

Other calls during the past week, some officially from the campaign and others run independently, included an Asian Americans, Native Hawaiian and Pacific Islanders call moderated by New York Rep. Grace Meng as well as an "Out for Kamala Harris" call co-hosted by the Human Rights Campaign and other groups, which featured actors Raven-Symoné and George Takei.

"I stan Kamala -- here's the situation. I need someone that I'm proud to say runs the country that I'm in ... I want someone that represents me for this country, and that's who she is," Raven-Symone said.

The official campaign -- and even members of Harris' family -- have tried to galvanize the online momentum as well.

On Thursday evening, the campaign hosted a "Young Voters for Biden" call, where, according to organizers, more than 4,000 users registered to get instructed on how to capitalize on the buzz of energy surrounding Harris from younger Democrats.

Some of the most impassioned rallying calls came from one of the Gen Z "special guests," Florida Rep. Maxwell Frost, who acknowledged the flood of coconut and coconut trees in the chatroom -- a reference to internet memes calling back to remarks by Harris -- while cautioning the energy can't just stop with memes.

"I know we're all excited. I see the coconuts. Everyone's falling out of a coconut tree -- that's sick. Congratulations. But what I need you to do -- make sure that you don't let your fight and your excitement end online," Frost said.

A separate videoconference hosted by Black LGBTQ+ advocates on Thursday was not hosted by the Harris campaign, but featured a surprise appearance by one of its key faces.

Second gentleman Doug Emhoff made a brief appearance where he shared more details on where he was -- getting coffee in Los Angeles after a SoulCycle class -- when he found out that Biden dropped out and that Harris would be running for president.

"I was actually with a gay couple friend of mine doing SoulCycle in West Hollywood … [afterwards] we're out there having coffee, messing around and talking, and … people are coming up to me," Emhoff said of the news the president was leaving the race and endorsing his wife.

ABC News' Katrina Davis, Abby Cruz, Davi Merchan, Gabriella Abdul-Hakim and Tommy Barone contributed to this report.