AMNA NAWAZ: Vice President Kamala Harris is starting to lay out her game plan against Donald Trump.

Speaking in Milwaukee, Harris told voters the November election will be a -- quote -- "choice between freedom and chaos."

The trip comes as Harris is getting more support from powerful allies back in Washington.

KAMALA HARRIS, Vice President of the United States (D) and U.S. Presidential Candidate: Thank you.

LAURA BARRON-LOPEZ: In Milwaukee today, Vice President Kamala Harris hit the ground running... KAMALA HARRIS: Good afternoon, Wisconsin.

(CHEERING) (APPLAUSE) LAURA BARRON-LOPEZ: ... and got the crowd going.

(APPLAUSE) (CHEERING) LAURA BARRON-LOPEZ: Her first campaign rally of the 2024 race in a key battleground state, wasting no time after being thrust into the limelight as the de facto Democratic nominee.

KAMALA HARRIS: I will spend the coming weeks continuing to unite our party so that we are ready to win in November.

(CHEERING) LAURA BARRON-LOPEZ: Harris has secured enough delegate support to win the nomination.

A blitz of big-name meetings among state delegations, including her home state of California, brought her over the threshold barely a day after President Biden dropped out of the race on Sunday.

A surge in campaign organizing has broken records.

As of this morning, the Harris campaign raised more than $100 million from 1.1 million donors since Sunday afternoon.

More than 62 percent of them were first-time donors, according to the campaign.

And 58,000 people signed up to volunteer.

That's more than 100 times an average day for the campaign.

KAMALA HARRIS: We just had the best 24 hours... (CHEERING) (APPLAUSE) KAMALA HARRIS: ... of grassroot fund-raising in presidential campaign history.

(CHEERING) (APPLAUSE) LAURA BARRON-LOPEZ: And Democrats like her chances in the latest PBS News, NPR, and Marist poll, a statistical tie with Harris trailing the Republican nominee, Donald Trump, by just one point.

Meanwhile, President Biden returned to the White House today after isolating in Rehoboth Beach, Delaware, with COVID-19.

His withdrawal from the race over the weekend followed weeks of immense pressure from inside his own party.

Now, among many Democrats, a sense of relief as the endorsements for Harris continue to pile up.

SEN. CHUCK SCHUMER (D-NY): We are here today to throw our support behind Vice President Kamala Harris.

LAURA BARRON-LOPEZ: Today, Senate Majority Leader Chuck Schumer and House Minority Leader Hakeem Jeffries joined in backing her nomination.

REP. HAKEEM JEFFRIES (D-NY): We're going to hold the Senate.

We're going to win the House.

We're going to elect Kamala Harris as our next president in November.

LAURA BARRON-LOPEZ: Notably, Senator Bernie Sanders, a leading progressive voice, stopped short of a full-out endorsement, calling on Harris to outline more of her policies.

SEN. BERNIE SANDERS (I-VT): If she is prepared to campaign around an agenda that speaks to the needs of the working class of this country, she's going to win the election, and win it big, in my view.

LAURA BARRON-LOPEZ: On a press call today, the Republican nominee, Trump, took new aim at Harris' record.

DONALD TRUMP, Former President of the United States (R) and Current U.S. Presidential Candidate: If she becomes president, Kamala Harris will make the invasion exponentially worse.

And just like she did with San Francisco, just like she did with the border, our whole country will be permanently destroyed.

LAURA BARRON-LOPEZ: He also said he's willing to debate Harris more than once.

DONALD TRUMP: And I think if you're the Democrat nominee or the Republican nominee, you really have an obligation to debate.

So I think it's very important.

LAURA BARRON-LOPEZ: Meanwhile, Harris has her eyes on possible running mates to join her on the ticket.

GOV.

ANDY BESHEAR (D-KY): Well, I'm going to keep any of the details of that call personal.

But what she did is, she called and asked for my support, and I willingly gave it.

LAURA BARRON-LOPEZ: Among the potential names, Kentucky Governor Andy Beshear and Illinois Governor J.B. Pritzker, both of whom are being considered for the job.

GOV.

J.B. PRITZKER (D-IL): Look, I love being the governor of the state of Illinois, and I have been out on the campaign trail fighting hard for Democrats to win.

I'm going to continue to do that.

And I'm very interested in making sure that Kamala Harris becomes the next president of the United States.

LAURA BARRON-LOPEZ: High-stakes decisions for the Harris team to make in a race completely turned on its head.

As Harris launches her expedited campaign, President Biden is preparing to address the nation tomorrow evening from the Oval Office.

This will be the first time the president has been seen publicly since he ended his reelection campaign on Sunday.

AMNA NAWAZ: And, Laura, you have reported now that Harris has secured enough delegates to secure that nomination for her party, so walk us through what could happen next.

Will she be officially the nominee before or during the convention?

LAURA BARRON-LOPEZ: So, tomorrow, the Democratic National Committee members who sit on the Rules Committee are going to meet, and they are going to vote on a plan for nominating -- for the nominating process.

And according to a copy of that plan obtained by PBS "News Hour," anyone who challenges Vice President Harris would have to file formal paperwork with the DNC, obtain 300 delegate signatures, no more than 50 from each state, and meet legal qualifications to be president.

The bottom line, Amna, is that DNC sources have made clear that they want to have their presidential nominee named by August 7.

And they're going to be establishing an electronic voting process, so, that way, they can hold a virtual roll call vote between - - some time between August 1 and August 7.

And they want to do this because they're trying to defend against Republican lawsuits that would potentially block their nominee from ballot access.

AMNA NAWAZ: Meanwhile, you mentioned in your report we have got new polling out in our PBS/NPR/Marist polling.

What does that show us in terms of how voters are reacting to President Biden's decision to step aside?

LAURA BARRON-LOPEZ: So some key findings from our latest poll.

There's overwhelming support for Biden's decision to step aside; 87 percent of national adults said it was the right decision.

And then, when it comes to enthusiasm, 46 percent of Democrats said that they are more likely to vote now that Biden was no longer the nominee.

And then another key finding, Amna, is that more voters -- there are voters that have not made up their mind about Harris.

And so there's more that haven't made up their mind about her than those who are already set in what they think about Donald Trump.

AMNA NAWAZ: You have also been reporting on her search to find a running mate.

What do you know so far?

LAURA BARRON-LOPEZ: So, according to sources close to the campaign, I'm told that Vice President Harris is currently considering 10 candidates for vice president.

And the ones that we know so far are North Carolina Governor Roy Cooper, Pennsylvania Governor Josh Shapiro, Minnesota Governor Tim Walz, as well as Arizona Senator Mark Kelly, Michigan Governor Gretchen Whitmer, and J.B. Pritzker of Illinois, the governor there, as well as Cedric Richmond and Kentucky Governor Andy Beshear.

Now, Governor Gretchen Whitmer of Michigan reiterated to reporters today that she has no interest in leaving Michigan, and she said that she hasn't submitted any type of formal documents to be vetted for the vice presidency.

AMNA NAWAZ: I know, from time to time, you get a chance to listen in on these focus groups of voters.

What have they been saying about Vice President Harris' candidacy now?

LAURA BARRON-LOPEZ: I sat on -- sat in on a focus group that was conducted by never-Trumper Sarah Longwell's firm, and this was a swing voter focus group.

So these are people that voted for Donald Trump in 2016 and then voted for Joe Biden in 2020.

And some were excited about Harris' potential to win the nomination.

KIRBY, Georgia: I just feel like it'll be like a breath of fresh air.

I feel like it'll be like a new beginning, instead of feeling like you're watching a rerun, because Trump has already been in office.

So I feel like Harris would definitely bring a new kind of, like, dynamic to her ideas, where she wants to take the world in the next four years.

So, I mean, I think it's a good decision.

LAURA BARRON-LOPEZ: That's Kirby from Georgia.

And a number of the voters in the focus group said that they were excited about the idea of her going head to head with Donald Trump.

There was one voter, Sumanth from Georgia, said that he wasn't necessarily happy with Kamala Harris as an option and that he is likely to reluctantly go back to Donald Trump.

SUMANTH, Georgia: Four years, she's been in the White House.

She's been the vice president.

And did she do anything?

No.

I have no idea what she even did.

So I feel like -- like, Americans are not being given a good choice here.

Like, we're just given -- we're being given the bread to Trump out of both choices.

LAURA BARRON-LOPEZ: Sumanth from Georgia was the only one in that group, Amna, of eight swing voters who said that he felt as though he had to go back to Donald Trump after Kamala Harris is launching her presidential campaign.

The other seven voters said that they would ultimately vote for Kamala Harris.

And if I could just add one more thing about the nomination process, Amna, it's that, when they ultimately vote on this electronic process tomorrow night, the DNC, it means that they are likely to have a nominee ahead of their physical convention in Chicago, which is slated for August 19 through 22.

So we are likely to see a nominee named in a very quick time frame here.

AMNA NAWAZ: That is our White House correspondent, Laura Barron-Lopez, reporting.

Laura, thank you.

LAURA BARRON-LOPEZ: Thank you.