Walz, 60, a liberal Democrat, won re-election to 2022 as Minnesota governor.
He is a member of the socialist Democratic-Farmer-Labor Party.
"Don't ever shy away from our progressive values," Walz, in a "White Dudes for Harris" call last week, told fellow Democrats. "One person's socialism is another person's neighborliness."
While Walz isn't from one of the crucial “blue wall” states of Wisconsin, Michigan and Pennsylvania, where both sides believe they need to win, he's right next door. He also could ensure that Minnesota stays in the hands of Democrats.
When Democratic Gov. Mark Dayton decided not to seek a third term in 2018, Walz campaigned and won the office on a “One Minnesota” theme.
Walz and lawmakers eliminated nearly all of the state abortion restrictions enacted in the past by Republicans, protected controversial "gender-affirming care" for transgender youth, and legalized the recreational use of marijuana.
Rejecting Republican pleas that the state budget surplus be used to cut taxes, Democrats funded free school meals for children, free tuition at public colleges for students in families earning under $80,000 a year, a paid family and medical leave program, and health insurance coverage for illegal immigrants.
Harris' choice of Walz was confirmed by three people familiar with the decision who spoke to The Associated Press on condition of anonymity because it had not been made public.
