US Vice-President Kamala Harris on Tuesday selected Minnesota Governor Tim Walz, 60, as her vice-presidential running mate, adding the folksy and popular Midwestern state executive to the Democratic ticket as the party seeks to hold onto key Northern battleground states this fall.

Harris will hold her first rally with Walz on Tuesday in Philadelphia, the first stop in a four-day tour of battleground states that includes visits to Michigan, Wisconsin, Nevada and elsewhere.

In picking Walz, she has selected a politician with executive governing experience, and signaled the importance of Midwestern battleground states such as Wisconsin and Michigan. A two-term governor and current chairman of the Democratic Governors Association, Walz is also a hunter and gun owner, which can often help candidates connect in rural areas.

Walz wasn't widely known outside of Minnesota before his name appeared on Harris shortlists. But he gained some Democratic fans outside his state in recent weeks for television interviews that hit at former president Donald Trump and his running mate Ohio Senator J.D. Vance without being overly nasty. He called the pair "weird'', a word that went viral among Democrats and on the internet.

Walz now faces introducing himself to the country with about three months left before the election, including a potential debate against Vance.

The choice of a running mate for Harris was among the most closely watched decisions of her fledgling campaign, as she sought to bolster the ticket's prospects for victory in November and rapidly find someone who could be a governing partner.

In recent days, Governor Josh Shapiro of Pennsylvania was perceived to be the front-runner over Walz and Arizona Senator John Kelly, but Walz was also seen by many as a safer choice for Harris because of his liberal stands and that Shapiro had come under fire from some progressives in the party and fellow Democrats. Shapiro especially received heavy scrutiny recently over his response to pro-Palestinian protests that emerged in the wake of the Israel-Hamas war.

It has been about two weeks since President Joe Biden announced he wouldn't seek reelection and Harris quickly moved to lead the Democratic ticket into the Nov 5 election against Trump, becoming the first black and South Asian American nominee for a major US party's White House campaign.

The most recent poll from CBS News shows Harris, 59, and Trump, 78, in a tight race nationally, with the Democrat holding a one-point lead over Trump.

Agencies contributed to this report.

aiheping@chinadailyusa.com