Kamala Harris, the Democratic Party’s candidate in the United States presidential election, has chosen Minnesota Governor Tim Walz as her running mate.

Harris announced Walz’s selection in a text message to supporters on Tuesday and will introduce him at a rally in Philadelphia later in the day.

“Tim is a battle-tested leader who has an incredible track record of getting things done for Minnesota families. I know that he will bring that same principled leadership to our campaign, and to the office of the vice president,” she said in her message.

In a post on X, she said she was “proud” to choose Walz as her running mate.

“As a governor, a coach, a teacher, and a veteran, he’s delivered for working families like his. It’s great to have him on the team,” Harris said on X.

In response, Walz said it was the “honour of a lifetime” to be Harris’s VP pick “I’m all in. It reminds me a bit of the first day of school. So, let’s get this done, folks!” he posted on X.

Harris’s choice of a progressive policy champion and a plain speaker from America’s heartland is aimed at helping her win over the rural, white voters in the November 5 polls.

Harris, the first woman and first Black and South Asian person to serve as vice president, considered a broad field of candidates during a fast vetting process in the race for the White House, after President Joe Biden ended his re-election bid on July 21.

Walz, 60, was elected to a Republican-leaning district in the US House of Representatives in 2006 and served 12 years before being elected the governor of the US state of Minnesota and re-elected to that position in 2022. His nomination would bring to the presidential ticket a record of defeating Republicans in a Midwestern state.

A veteran of the US Army National Guard, Walz serves as co-chair of the Democratic National Convention’s rules committee.

As governor, he has pushed a progressive agenda including free school meals, goals for tackling climate change, tax cuts for the middle class and expanded paid leave for Minnesota workers.

Walz has long advocated for women’s reproductive rights and oversaw state approval of the right to abortion and protected gender-affirming care. But he has also displayed a conservative bent while representing a rural district in the US House, defending agricultural interests and backing gun rights.

Harris, the 59-year-old daughter of immigrants from Jamaica and India, is adding a popular Midwestern politician whose home state votes reliably for Democrats in presidential elections but is close to Wisconsin and Michigan, two crucial battleground states.

She will hold a major rally with her vice presidential pick later on Tuesday in Philadelphia in the swing state of Pennsylvania, followed by rallies in Wisconsin, Michigan, North Carolina, Arizona and Nevada through Saturday.

The duo will face off against the Republican nominee and former President Donald Trump and his running mate JD Vance in the November election.

Trump’s campaign on Tuesday slammed Walz as a left-wing radical.

“If Walz won’t tell voters the truth, we will: just like Kamala Harris, Tim Walz is a dangerously liberal extremist,” Karoline Leavitt, Trump’s campaign press secretary, said in a statement.

Walz has previously attacked Trump and Vance as “weird”, a catchy insult that has been picked up by the Harris campaign, social media and Democratic activists.