NORMAN, Okla. — President Joe Biden on Friday formally apologized to Native Americans for the “sin” of a government-run boarding school system that for decades forcibly separated Indian children from their parents, calling it a “stain on American history” in the first to visit his native country.

“It’s a sin on our souls,” Biden said, his voice full of anger and emotion. “Quite frankly, there is no excuse that the apology took 50 years.”

Biden spoke about the abuse and deaths of Native children that resulted from federal government policies, as he noted that the shameful history remained unknown and needed to be told. The president detailed how his policies sought to support Native Americans with jobs and new infrastructure.

Democrats hope Biden’s visit to the Gila River Indian Community grounds on the outskirts of metro Phoenix in Arizona will also provide a boost to Vice President Kamala Harris’ turnout effort in a key battleground state.

Biden, whose presidency is winding down, promised tribal leaders nearly two years ago that he would visit Indian Country.

The president, in an exchange with reporters Thursday before leaving for Arizona, said apologizing for the U.S. government’s role in abusing and neglecting Native children was “something that should have been done a long time ago.” For decades, federal boarding schools have been used to assimilate children into white society, according to the White House.

The moment will also give Biden a chance to highlight his and Harris’ support for tribal nations, a group that has historically favored Democrats, in a state he won by just 10,000 votes in 2020.

The race between Harris and former President Donald Trump is expected to be just as close, and both campaigns are doing everything they can to improve voter turnout among grassroots supporters.

“The race is now a turnout,” said Mike O’Neil, a nonpartisan pollster based in Arizona. “Trend lines have been remarkably stable. The question is which candidate will be able to turn off voters in a race that appears destined to be decided by narrow margins.”

Biden has been used sparingly on the campaign trail by Harris and other Democrats since he ended his re-election campaign in July.

But analysts say Biden could help Harris in her appeal to Native American voters — a group that has trailed others in turnout rates.

In 2020, there was a surge in turnout in Arizona’s tribal turf as Biden defeated Trump to become the first Democratic presidential candidate to win the state since Bill Clinton in 1996.

Biden is making the visit in his official capacity, and the official apology — something the tribes have long sought — seems sure to draw attention among Native Americans across the country.

At least 973 Native American children died in the US government’s abusive boarding school system over a 150-year period ending in 1969, according to an Interior Department investigation that demanded an apology from the US government.

At least 18,000 children, some as young as 4, were taken from their parents and forced to attend schools that tried to assimilate them.

“President Biden deserves credit for finally bringing attention to the issue and other issues affecting the community,” said Ramona Charette Klein, 77, a boarding school survivor and charter member of the Turtle Mountain Band of Chippewa. “I think that will reflect well on Vice President Harris and I hope that momentum continues.”

She added that whoever is the next president must follow through with concrete actions and begin to repair the devastation boarding schools have brought to the tribes.

Democrats have stepped up their outreach to Native American communities.

Both Harris and her running mate, Minnesota Gov. Tim Walz, met with tribal leaders in Arizona and Nevada this month. And Clinton, who served as a surrogate for Harris, met last week in North Carolina with the chairman of the Lumbee tribe.

The Democratic National Committee recently launched a six-figure ad campaign targeting Native American voters in Arizona, North Carolina, Montana and Alaska through digital, print and radio ads.

Democratic Rep. Ruben Gallego, who is locked in a competitive race with Republican Kari Lake for Arizona’s open Senate seat, has visited all 22 federally recognized tribes in Arizona.

Harris recently kicked off a campaign rally in Chandler, near the site of the Gila River Reservation, with a shout-out to the tribal leader.

She also reminded the crowd that she was the first vice president to visit the reservation. She and husband Doug Emhoff visited the community last year.

“I strongly believe that the relationship between tribal nations and the United States is sacred … and that we must honor tribal sovereignty, embrace our trust in treaty obligations and ensure tribal self-determination,” Harris said.

The White House says Biden and Harris have built a substantial track record with Native Americans over the past four years.

He designated the sacred Avi Kwa Ame, a desert mountain in Nevada and the Baaj Nwaavjo I’tah Kukveni-Ancestral Footprints of the Grand Canyon in Arizona as national monuments and restored the boundaries for Bears Ears National Monument in Utah.

In addition, the administration directed nearly $46 billion in federal spending to tribal nations. The money helped bring electricity to a reservation that never had electricity, expand high-speed Internet access, improve water sanitation, build roads and more.

Biden picked former New Mexico Rep. Deb Haaland as interior secretary, the first Native American appointed to a Cabinet position. Haaland is a member of Laguna Pueblo in New Mexico.

She, in turn, ordered a comprehensive review in June 2021 of the troubling legacy of the federal government’s boarding school policies, prompting Biden to issue a formal apology.

“He’s made commitments to Indian Country and he’s followed through on every one of those commitments,” Haaland said.

Thom Reilly, co-director of the Center for an Independent and Sustainable Democracy at Arizona State University, said both the Harris and Trump campaigns — and their allies — have made a remarkable effort at micro-targeting in Arizona.

Harris, Reilly noted, also focused on reducing Trump’s lead among Mormon voters in the state, a group that has historically favored Republicans. Trump, meanwhile, has placed a particular focus on young men as the campaign seeks to reduce the Democrats’ advantage with younger voters.

“They’re pulling out every stop just to see if they can wrangle a few more votes here and there,” Reilly said. “The Indian community is one of those groups that Harris hopes will over-perform and help make a difference.”