The Minnesota governor is set to arrive in Los Angeles later in the evening after speaking at a campaign reception in Montecito, in Santa Barbara County.
He's also scheduled to appear on "Jimmy Kimmel Live."
Meanwhile, Vice President Kamala Harris was in North Carolina this weekend to meet with local officials to get an update on Hurricane Helene recovery efforts. She's also preparing for several interviews this week.
She recently appeared on the popular "Call Her Daddy" podcast where she discussed abortion, sexual abuse and other issues that resonate with women, working in some digs at her GOP opponent along the way.
The interview was part of a broader media outreach effort by Harris and her running mate Walz, as the Democrats seek to boost their support in the final 30 days of the campaign against Republicans Donald Trump and JD Vance.
Harris has taped an interview with CBS' "60 Minutes" that will air Monday night. She is booked Tuesday on Howard Stern's satellite radio show, ABC's "The View" and "The Late Show" with Stephen Colbert on CBS.
Nearly a week after his verbal stumbles in the only vice presidential debate, Walz used his debut campaign appearance on a Sunday news show to try to fend off criticism of his stand on abortion rights and to "own up" to past misstatements.
Meanwhile, Trump on Sunday visited Wisconsin for the fourth time in eight days as his campaign showers attention on a pivotal state where Republicans fret about his ability to match Democrats' enthusiasm and turnout machine.
"They say that Wisconsin is probably the toughest of the swing states to win," Trump said in his opening remarks at an airplane hangar in a rural Juneau where the overflow crowd spilled out on to the tarmac. "I don't think so."
Wisconsin is perennially tight in presidential elections but has gone for the Republicans just once in the past 40 years, when Trump won the state in 2016. A win in November could make it impossible for Harris to take the White House.
This is a developing story. This article will continue to be updated as more information becomes available.
The Associated Press contributed to this report.