On a three-hour organizing call with over 100,000 attendees, numerous high-profile progressive democrats came out to support Vice President Kamala's Harris' presidential bid.

Sens. Bernie Sanders and Elizabeth Warren, Reps. Joaquin Castro, Ro Khanna, Ilhan Omar and Jamie Raskin and UAW President Shawn Fain all showed up as well as members of the uncommitted movement who had not yet endorsed Harris but strongly hope she'll win them over in the next few months.

"The energy and the momentum in this election is on our side. And I am so inspired by the organizing in support of Vice President Harris, starting with the win with black women that mobilized a massive zoom call. And now here tonight, we have progressives coming together," Warren said on the call.

Sanders, who has not officially said he endorses Harris -- although he has encouraged voters to go out and support the candidate -- told attendees that "Trump must be defeated" and Harris "must be elected." He noted that it's "imperative that Democrats gain control over the House and the Senate."

"And we in the progressive movement must do all that we can to make that happen," he added.

"I don't know if I can add to what has already been said tonight, but my message is pretty clear, and that is all of us together must do everything that we can to defeat Donald Trump and elect Kamala Harris as our next president," said Sanders.

-ABC News' Gabriella Abdul-Hakim

Vice President Kamala Harris' presidential campaign is promoting pre-orders for a campaign yard sign with a mockup image featuring her last name and tape and question marks over where her yet-to-be-announced running mate's last name would be.

"Be one of the first to proudly display your support for Kamala Harris and her running mate," the campaign said on its website.

-ABC News' Oren Oppenheim

Republican vice presidential candidate JD Vance is scheduled to give remarks in the same states on the same days as Vice President Kamala Harris this week, the Trump-Vance campaign announced, as Harris embarks on a battleground state tour.

Vance is scheduled to speak at noon ET in Philadelphia on Tuesday. The event comes as Harris is set to hold a rally with her yet-to-be-announced running mate Tuesday night in the city.

On Wednesday, he is scheduled to deliver remarks in the Detroit suburb of Shelby Township, Michigan, and Eau Claire, Wisconsin, as Harris also campaigns in those states then.

Then on Thursday, he is set to speak in Raleigh and Oakboro in North Carolina, aligning with Harris' scheduled visit to the state.

-ABC News' Hannah Demissie

Bon Iver will join Harris and her running mate on Wednesday in Eau Claire, Wisconsin -- where the Grammy-winning indie folk band was founded -- for a "special performance" as part of the campaign's battleground state tour, the Harris campaign announced on Monday.

-ABC News' Gabriella Abdul-Hakim, Fritz Farrow, Will McDuffie and Isabella Murray