Fred Harris, a former U.S. senator from Oklahoma, presidential hopeful and populist who championed Democratic Party reforms in the turbulent 1960s, died Saturday. He was 94.

Harris’ wife, Margaret Elliston, confirmed his death to The Associated Press. He had lived in New Mexico since 1976.

“Fred Harris passed peacefully early this morning of natural causes. He was 94. He was a wonderful and beloved man. His memory is a blessing,” Elliston said in a text message.

Harris served eight years in the Senate, first winning in 1964 to fill a vacancy, and made unsuccessful bid for the presidency in 1976.

“I am deeply saddened to learn of the passing of my longtime friend Fred Harris today,” Democratic New Mexico Gov. Michelle Lujan Grisham wrote in a post to social media. “Harris was a towering presence in politics and in academia, and his work over many decades improved New Mexico and the nation.  He will be greatly missed.”

Democratic Sen. Martin Heinrich of New Mexico said in a statement that “New Mexico and our nation have lost a giant,” describing him as a “tireless champion of civil rights, tribal sovereignty and working families.”

It fell to Harris, as chairman of the Democratic National Committee in 1969 and 1970, to help heal the party’s wounds from the tumultuous national convention in 1968 when protesters and police clashed in Chicago.

He ushered in rule changes that led to more women and minorities as convention delegates and in leadership positions.

“I think it’s worked wonderfully,” Harris recalled in 2004, when he was a delegate to the Democratic National Convention in Boston. “It’s made the selection much more legitimate and democratic.”

“The Democratic Party was not democratic, and many of the delegations were pretty much boss-controlled or -dominated. And in the South, there was terrible discrimination against African Americans,” he said.

Harris ran unsuccessfully for the Democratic presidential nomination in 1976, quitting after poor showings in early contests, including a fourth-place win in New Hampshire. The more moderate Jimmy Carter went on to win the presidency.

Harris moved to New Mexico that year and became a political science professor at the University of New Mexico. He wrote and edited more than a dozen books, mostly on politics and Congress. In 1999 he broadened his writings with a mystery set in Depression-era Oklahoma.

Throughout his political career, Harris was a leading liberal voice for civil rights and anti-poverty programs to help minorities and the disadvantaged. Along with his first wife, LaDonna, a Comanche, he also was active in Native American issues.

“I’ve always called myself a populist or progressive,” Harris said in a 1998 interview. “I’m against concentrated power. I don’t like the power of money in politics. I think we ought to have programs for the middle class and working class.”

“Today ‘populism’ is often a dirty word because of how certain leaders wield power,” Heinrich said in his statement Saturday. “But Fred represented a different brand of populism — one that was never mean or exclusionary. Instead, Fred focused his work and attention on regular people who are often overlooked by the political class.”

Harris was a member of the National Advisory Commission on Civil Disorders, the so-called Kerner Commission, appointed by then-President Lyndon Johnson to investigate the urban riots of the late 1960s.

The commission’s groundbreaking report in 1968 declared, “our nation is moving toward two societies, one black, one white — separate and unequal.”

Thirty years later, Harris co-wrote a report that concluded the commission’s “prophecy has come to pass.”

“The rich are getting richer, the poor are getting poorer and minorities are suffering disproportionately,” said the report by Harris and Lynn A. Curtis, president of the Milton S. Eisenhower Foundation, which continued the work of the commission.

Norman Ornstein of the American Enterprise Institute said Harris rose to prominence in Congress as a “fiery populist.”

“That resonates with people…the notion of the average person against the elite,” Ornstein said. “Fred Harris had a real ability to articulate those concerns, particularly of the downtrodden.”

In 1968, Harris served as co-chairman of the presidential campaign of then-Vice President Hubert Humphrey. He and others pressed Humphrey to use the convention to break with Johnson on the Vietnam War. But Humphrey waited to do so until late in the campaign, and narrowly lost to Republican Richard Nixon.

“That was the worst year of my life, ’68. We had Dr. Martin Luther King killed. We had my Senate seatmate Robert Kennedy killed and then we had this terrible convention,” Harris said in 1996.

“I left the convention — because of the terrible disorders and the way they had been handled and the failure to adopt a new peace platform — really downhearted.”

After assuming the Democratic Party leadership post, Harris appointed commissions that recommended reforms in the procedures for selecting delegates and presidential nominees. While lauding the greater openness and diversity, he said there had been a side effect: “It’s much to the good. But the one result of it is that conventions today are ratifying conventions. So it’s hard to make them interesting.”

“My own thought is they ought to be shortened to a couple of days. But they are still worth having, I think, as a way to adopt a platform, as a kind of pep rally, as a way to get people together in a kind of coalition-building,” he said.

Harris was born Nov. 13, 1930, in a two-room farmhouse near Walters, in southwestern Oklahoma, about 15 miles from the Texas line. The home had no electricity, indoor toilet or running water.

At age 5 he was working on the farm and received 10 cents a day to drive a horse in circles to supply power for a hay bailer.

He worked part-time as a janitor and printer’s assistant to help for his education at University of Oklahoma. He earned a bachelor’s degree in 1952, majoring in political science and history. He received a law degree from the University of Oklahoma in 1954, and then moved to Lawton to practice.

In 1956, he won election to the Oklahoma state Senate and served for eight years. In 1964, he launched his career in national politics in the race to replace Sen. Robert S. Kerr, who died in January 1963.

Harris won the Democratic nomination in a runoff election against J. Howard Edmondson, who left the governorship to fill Kerr’s vacancy until the next election. In the general election, Harris defeated an Oklahoma sports legend — Charles “Bud” Wilkinson, who had coached OU football for 17 years.

Harris won a six-year term in 1966 but left the Senate in 1972 when there were doubts that he, as a left-leaning Democrat, could win reelection.

Harris married his high school sweetheart, LaDonna Vita Crawford, in 1949, and had three children, Kathryn, Byron and Laura. After the couple divorced, Harris married Margaret Elliston in 1983. A complete list of survivors was not immediately available Saturday.