"As a governor, a coach, a teacher, and a veteran, he's delivered for working families like his," Harris posted on X, formerly known as Twitter, Tuesday.

Harris formally clinched the Democratic nomination Monday and is expected to appear at a rally with Walz in Philadelphia on Tuesday evening.

Walz said it was an honour of a lifetime to join the campaign.

"I'm all in," Walz said in a post on social media.

The search for a running mate began just two weeks ago, after President Joe Biden removed himself as the nominee amid concerns over his age and endorsed Harris.

In the turbulent days that followed, Walz received national attention for his plain-spoken television appearances, and was credited for coining the increasingly popular Democratic talking point that their Republican opponents are "just weird."

Walz, 60, is a military veteran, retired educator and union supporter whose state shares a 885-kilometre border with Canada.

"Between Walz and Harris' background in Canada, these are two people that will have a good understanding of the relationship between the two countries," said Matthew Lebo, a specialist in U.S. politics at Western University in London, Ont.

Harris, who lived in Montreal as a teenager, is expected to be guided by Biden's road map as she navigates America's relationship with Canada.

Biden's tenure has been described as more stable than his predecessor when it comes to U.S.-Canada relations, but not much different from former president Donald Trump's administration.

Trump pushed to renegotiate of the old North American Free Trade Agreement.

It was replaced with the U.S.-Mexico-Canada Agreement, which Canada's government heralded as a success, but which Harris voted against, saying it didn't do enough to protect American workers or the environment.

Trump also introduced billions of dollars' worth of tariffs, particularly on Chinese imports, and he has threatened more if he wins a second term in office.

Lebo said it's likely Walz understands the value of trade between Canada and the United States.

The Business Council of Canada website describes the relationship with Minnesota as more than just a shared love of hockey with its neighbours to the north. Trade ties are extensive, especially when it comes to energy and agriculture.

"Ontario and Minnesota do billions of dollars in two-way trade every year. We agreed on the need to protect and grow our strong economic ties, including our growing agriculture and energy sectors," Premier Doug Ford posted on social media after Walz visited Queen's Park in June.

Walz also seems "Canadian" in terms of his temperament and values, Lebo said.

"Minnesota may be the most Canadian-like state," Lebo said.

He has also pushed social policies in line with the current Canadian government, Lebo said.

Walz and fellow lawmakers have eliminated nearly all of the state's abortion restrictions, protected gender-affirming care for transgender youth and legalized the recreational use of marijuana.

Minnesota Democrats also funded free school meals for children and free tuition at public colleges for students in families that earning less than $80,000 a year. Walz has been praised for putting state funds toward health insurance coverage, regardless of a person's immigration status.

Lebo said Walz may be criticized for his response to protests after the murder of George Floyd by a Minneapolis police officer in 2020 and his administration's oversight of some pandemic-era programs.

The governor, with a "Minnesota nice" demeanour, may help to build an important bridge between the Democrats and voters in key battleground states like Michigan, Pennsylvania and Wisconsin. Trump won those states in 2016 and they swung to Biden in 2020.

Harris's decision to pick Walz as her running mate shows she is looking to pull in more voted from white, working class men Lebo said. There were concerns that she would have less success with those voters than Biden, he said, and they could be critical for a Democratic win.

"She was looking for someone who might appeal to independent voters," Lebo said.

This report by The Canadian Press was first published Aug. 6, 2024.

-- With files from The Associated Press.