DENVER — Ben Nighthorse Campbell, the former senator and U.S. representative of Colorado known for his passionate advocacy of Native American issues, died Tuesday. He was 92.

Campbell died of natural causes surrounded by his family, his daughter, Shanan Campbell, confirmed to The Associated Press.

Campbell, a Democrat who stunned his party by joining the Republican Party, stood out in Congress as much for his unconventional dress — cowboy boots, bolo ties and ponytail — as his defense of children’s rights, organized labor and fiscal conservatism.

A member of the Northern Cheyenne tribe, Campbell said his ancestors were among more than 150 Native Americans, mostly women, children and elderly men, killed by U.S. soldiers while camped under a flag of truce on Nov. 29, 1864. He helped sponsor legislation upgrading the Great Sand Dunes National Monument in southern Colorado, where the massacre happened, to a national park.

He served three terms in the House, starting in 1987. He then served two terms in the Senate, from 1993 to 2005.

The motorcycle-riding lawmaker and cattle rancher was considered a maverick even before he abruptly switched to the Republican Party in March 1995, angry with Democrats for killing a balanced-budget amendment in the Senate. His switch outraged Democratic leaders and was considered a coup for the GOP.

“I get hammered from the extremes,” he said shortly afterward. “I’m always willing to listen … but I just don’t think you can be all things to all people, no matter which party you’re in.”

Considered a shoo-in for a third Senate term, Campbell stunned supporters when he dropped out of the race in 2004 after a health scare.

“I thought it was a heart attack. It wasn’t,” said Campbell. “But when I was lying on that table in the hospital looking up at all those doctors’ faces, I decided then, ‘Do I really need to do this six more years after I’ve been gone so much from home?’ I have two children I didn’t get to see grow up, quite frankly.”

He retired to focus on the Native American jewelry that helped make him wealthy and was put on display at the Smithsonian Institution’s National Museum of the American Indian. He also worked on a line of outdoor gear with a California-based company, Kiva Designs, and became a senior policy adviser with the powerhouse law firm of Holland & Knight in Washington.

Campbell founded Ben Nighthorse Consultants which focused on federal policy, including Native American affairs and natural resources. The former senator also drove the Capitol Christmas Tree across the country to Washington, D.C., on several occasions.

In 1982, he was planning to deliver his jewelry to California, but bad weather grounded his plane. He was killing time in the southern Colorado city of Durango when he went to a county Democratic meeting and wound up giving a speech for a friend running for sheriff.

Democrats were looking for someone to challenge a GOP legislative candidate and sounded out Campbell during the meeting. “Like a fish, I was hooked,” he said.

His opponent, Don Whalen, was a popular former college president who “looked like he was out of a Brooks Brothers catalog,” Campbell recalled. “I don’t think anybody gave me any kind of a chance. … I just think I expended a whole lot of energy to prove them wrong.”

Campbell hit the streets, ripping town maps out of the Yellow Pages and walking door to door to talk with people. He recalled leaving a note at a house in Cortez where no one was home when he heard a car roar into the driveway, gravel flying and brakes squealing.

The driver jumped out, tire iron in hand, and screamed that Campbell couldn’t have his furniture. “Aren’t you the repossession company?” the man asked.

“And I said, ‘No man, I’m just running for office.’ We got to talking, and I think the guy voted for me.”

Campbell went on to win what he called the “most gentlemanly, friendly” race he was involved in. He never lost an election, moving from the Colorado House to the U.S. House and then the Senate.

Born April 13, 1933, in Auburn, California, Campbell served in the Air Force in Korea from 1951 to 1953 and received a bachelor’s degree from San Jose State University in 1957. He attended Meiji University in Tokyo from 1960 to 1964, was captain of the U.S. judo team in the 1964 Olympics and won a gold medal in the Pan American Games.

Campbell once called then-Interior Secretary Bruce Babbitt a “forked-tongued snake” for opposing a water project near the southern Colorado town of Ignacio, which Campbell promoted as a way to honor the water rights of the Southern Ute and Ute Mountain Ute tribes and was his most obvious legacy.

He clashed with environmentalists on everything from mining law and grazing reforms to setting aside land for national monuments.

Despite all this — or perhaps because of it — voters loved him. In 1998, Campbell won reelection to the Senate by routing Democrat Dottie Lamm, the wife of former Gov. Dick Lamm, despite his switch to the GOP. He was the only Native American in the Senate at the time.

“It didn’t change me. I didn’t change my voting record. For instance, I had a sterling voting record as a Democrat on labor. I still do as a Republican. And on minorities and women’s issues,” he said.