Election 2024 updates: Michelle Obama to speak at DNC this week

In a video posted on his X account, the Minnesota governor discussed what he called "not a normal week" since being named as Harris' running mate.

Walz confirmed some details reported previously by ABC News and others, including that he informed Harris' vetting team that he had not used a teleprompter before.

"Not a normal week, which is a good thing. Started by missing a call from the Vice President, pretty important one. And then got that call and honored to join the ticket with Kamala Harris to take us in a great direction," Walz said.

"After that, it has been a whirlwind. We got on a plane and we flew to Philly, and they told me that in an hour I'd be giving a speech and there would be a teleprompter, something I had never used in my life, so certainly terrified, but was lifted up by the folks in Philly."

-ABC News' Will McDuffie

Over the weekend, Harris closed out a cross-country tour that included stops in battleground states Pennsylvania, Wisconsin, Michigan, Georgia and Arizona, as well as North Carolina and Nevada.

New polling released Saturday showed Harris taking the lead over Trump in Pennsylvania, Michigan and Wisconsin among likely voters. The New York Times/Siena College polls showed Harris at 50% among likely voters in each state, while Trump polled at 46%.

Vance, too, campaigned in key 2024 states and made the rounds on the Sunday shows. During his cable news appearances, Vance reiterated campaign talking points on immigration and repeatedly hit Harris for not sitting down for extensive media interviews and laying out her agenda. Harris has done brief gaggles with reporters and said she'd unveil an economic policy platform this week.

Sen. JD Vance told ABC News he blamed Vice President Kamala Harris and the Biden administration's policies, such as ending "Remain in Mexico," for the ongoing migrant crisis.

When asked how he and Trump would accomplish their stated goal of mass deporting as many as 20 million immigrants – a proposal experts previously told ABC News would be a "nightmare" -- Vance said they would take a "sequential approach."

"I mean do you go knock on doors and ask people for their papers? What do you do," Jonathan Karl, "This Week" co-anchor, asked.

"You start with what's achievable," Vance said. "I think that if you deport a lot of violent criminals and frankly if you make it harder to hire illegal labor, which undercuts the wages of American workers, I think you go a lot of the way to solving the illegal immigration problem."

"I think it's interesting that people focus on, well, how do you deport 18 million people? Let's start with 1 million. That's where Kamala Harris has failed. And then we can go from there," Vance said.

-ABC News' Ivan Pereira

Vice President Kamala Harris attended a fundraiser in San Francisco Sunday where she maintained her campaign "will win this election," but cautioned donors to "not take anything for granted."

"I know there's a lot of enthusiasm out there," Harris said, adding, "And you know, I've never been one to really believe in the polls -- whether they're up or they're down."

"What we know is the stakes are so high and we can take nothing for granted in this critical moment," she continued. "So we will fuel our campaign as we have, with enthusiasm and optimism, but also with a deep commitment to the hard work it’s going to take, and to campaign."

Speaker Emerita Nancy Pelosi introduced Harris at the event, touting the accomplishments of the Biden-Harris administration and the background of vice presidential nominee Tim Walz, several times calling the Harris-Walz ticket "the freedom ticket."

"[Harris] makes us all so proud. She brings us so much joy. She gives us so much hope," Pelosi said, calling the vice president "politically very astute."

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