Obama told several thousand American Indian supporters that he would honor long-ignored treaty obligations and revamp health care and education on reservations across the United States. Such services have long suffered due to inadequate funding and the much criticized oversight of the Bureau of Indian Affairs.
"Few have been ignored by Washington for as long as Native Americans, the first Americans," Obama said. "That will change when I am president of the United States."
Obama said treaty commitments with Indian nations were "paramount to law" and could not be ignored when Washington makes funding decisions affecting Indian country. He characterized the Bureau of Indian Affairs as a bureaucracy out of touch with those it serves, and said the agency needs to be shaken up so it will perform better.
"You guys pay taxes too. You deserve to get decent services from Washington," he told the crowd in Crow Agency, Mont.
Earlier, in a private ceremony, the candidate was adopted into the Black Eagle family of the tribe under the name Awe Kooda Bilaxpak Kuuxshish, or "One Who Helps People Throughout the Land."
Crow Vice Chairman Cedric Black Eagle said a purification ceremony was performed in which the candidate faced east - the source of new life - and was prayed over by his adopted father, Hartford Black Eagle.
Tribal representatives from across Montana said it was the first time such a high-profile candidate had appeared on one of the state's reservations. The closest precedent, they said, was a visit to the Crow reservation by first lady Lady Bird Johnson in the 1960s.
"Here's a gentleman who could be president of the United States who is putting his hand out to us," said Roger Running Crane, vice chairman of the Blackfeet Tribe of northwest Montana. "It's great to see someone take an interest and see what is really happening with Indians today."
By reaching out to Indians, Obama was playing to a traditional Democratic constituency, but one with limited influence at the ballot box, said Montana State University-Billings political analyst Craig Wilson.
He said Native Americans represent about 6.5 percent of Montana's population, one of the highest percentages in the nation.
"It's good politics, certainly for a Democrat," Wilson said. "Will it matter in terms of the election? No."
During a prior stop in Billings, Mont., on Monday morning, Obama looked past the state's June 3 primary to focus on an anticipated November battle against Republican John McCain. He said electing the Arizona senator would amount to a third term for supporters of President Bush. And he took aim at the Republican party's close ties to lobbyists.
By contrast, he said, an Obama presidency would be modeled on the high standard of open government demonstrated in Montana, where Gov. Brian Schweitzer has pledged to allow public access to all of his meetings.
"I want to carry those same Montana values, those Montana values of openness and transparency, with me to the White House," Obama said.
He also made a stop Monday night at Montana State University in Bozeman, where he spoke to a crowd of about 7,000.
Obama stuck to common themes in his campaign, such as national security and weaning the country from its reliance on foreign oil.
"On June 3, we're going to bring this nomination to a close right here in Montana," he said.
As Obama stands on the verge of emerging the victor from a protracted primary battle with Sen. Hillary Rodham Clinton, a Clinton spokeswoman insisted it was "premature" to call the race over.
"We are campaigning in Montana with the idea that this is historic for Montana and every vote should count," said the spokeswoman, Kate Downen. "He still doesn't have the number of delegates he needs to claim victory."
Montana Republicans said an Obama win would be bad for the region's lucrative coal industry, on which they claim he would impose new taxes. Obama's remarks in Billings hit on the potential for other energy sources - such as solar, wind and biofuels - but not coal.
State Republican Chairman Erik Iverson said Obama also was out of step with Montana on gun issues and proposals to suspend the gas tax, which Obama opposes.
"He's just plain wrong for Montana on a lot of issues that we care about," Iverson said.