U.S. Rep. Tim Walz has selected state Rep. Peggy Flanagan of St. Louis Park as running mate in his campaign to be Minnesota’s next governor, hoping to both bolster his credibility with progressives and bring geographic balance as he mounts a bid from greater Minnesota.

“She has life experience that is different from mine but brought us to the same place, and always with joy and hopefulness,” Walz said in an interview Thursday. The DFL congressman from Mankato plans to introduce Flanagan to supporters Saturday at the Minneapolis American Indian Center, the first candidate for governor in 2018 from either party to select a running mate.

Flanagan, 38, is a two-term lawmaker from the western Twin Cities metro with deep roots in DFL activism. If Flanagan becomes lieutenant governor, she would be the state’s first American Indian elected to statewide office, and the highest ranking elected American Indian woman in U.S. history.

“We’ll have an opportunity for people of color, indigenous folks, those from marginalized communities, to have a seat at the table,” said Flanagan, who joined the Legislature after a 2015 special election.

Walz has been elected six times in a Republican-leaning district by appealing to independent voters, even winning past support from the National Rifle Association.

Flanagan, who was previously executive director of the Children’s Defense Fund-Minnesota, is beloved by Twin Cities progressive activists.

“She’s a powerhouse, and I can understand why he would pick her,” said Rep. Frank Hornstein, DFL-Minneapolis, who has not endorsed any candidate. “With this move, it’s definitely game on.”

Republicans will try to use the Flanagan selection to paint Walz as a captive of the DFL’s progressive, Twin Cities-centered base.

“Tim Walz’s campaign for governor has already hit an iceberg. His selection of hard-left progressive Peggy Flanagan doesn’t change that,” said John Rouleau, executive director of the Minnesota Jobs Coalition, a Republican-aligned political group. He added that Walz’s choice of Flanagan “is a desperate attempt to appease the most liberal activists in the DFL.”

Although Flanagan brings balance to the Walz candidacy, the running mates acknowledged some policy disagreements.

“I’m eager to join the ticket because Tim and I don’t always agree, but we have a healthy respect and admiration for each other,” Flanagan said. “I’m not afraid to tell Tim when I think he’s wrong.”

Flanagan immediately pointed to an issue that Walz’s DFL opponents will likely use against him: refugees.

In late 2015, Walz voted with Republicans in Congress to tighten screening procedures for refugees coming from Syria and Iraq. That put him sharply at odds with the increasingly diverse and progressive DFL, in which immigrants and their descendants from Somalia and other countries are an emerging force.

“I called Tim on the refugee issue, and I told him I thought it was the wrong vote,” Flanagan said.

Walz said he regrets it. “I thought it would reassure people about the security of the program,” he said. “It went counter to my entire life’s work.”

A longtime high school teacher and football coach, Walz, 53, also retired as a command sergeant major of the Army National Guard.

Flanagan has been a vocal opponent of efforts of Calgary-based Enbridge Inc. to replace an oil pipeline that cuts through northern Minnesota. The proposed Line 3 wouldn’t cross any reservations, but would run though lands on which the Ojibwe have treaty rights.

Walz, however, is close to the building trades unions, which are vehement supporters of the $2.9 billion pipeline project. He received more than $58,000 in his last election from the unions. Walz said pipelines are preferable to transporting oil by rail, and that the pipeline should be built, but only if it can be done safely and without disturbing treaty lands.

For whatever their policy differences, Walz and Flanagan said they have a long-standing personal bond that goes back to Walz’s time at what is known as “Camp Wellstone,” a grass roots training boot camp named for the late lion of Minnesota progressive politics. Flanagan was an instructor when Walz attended in 2005, as he geared up for his first run for Congress.

“The trainers looked at each other said, ‘Who is this guy?’ Flanagan said about Walz, who is known for his high energy approach.

The two seem to have an easy rapport, with Flanagan needling Walz about his Diet Mountain Dew habit. While Walz is still tied up with his duties in Washington, he can lean on Flanagan to be a full-time surrogate.

And, as he seeks support of the roughly 1,250 DFL delegates who will gather in Rochester in June to endorse a candidate for governor, the early Flanagan pick could cut into potential bases of support for the race’s other metro candidates, including state Reps. Erin Murphy and Paul Thissen, St. Paul Mayor Chris Coleman and State Auditor Rebecca Otto. One other DFL candidate hails from greater Minnesota, state Rep. Tina Liebling of Rochester.

Attorney General Lori Swanson is expected soon to announce a decision about her future plans, including a potential run for governor.