David H. Pryor, a liberal Democrat who won two terms as governor of Arkansas and three in the United States Senate, and who paved the way for the political rise of his young ally Bill Clinton in an era of changing racial attitudes in the South, died on Saturday at his home in Little Rock. He was 89.

His death was announced by his son Mark, himself a former two-term United States senator.

Mr. Pryor was 12 years older than Mr. Clinton, and they didn’t know each other well until they became accomplished politicians. But they had much in common. They both grew up in segregated small towns in Arkansas, raised by families of modest means and liberal outlook, who resisted pressures to scorn their Black neighbors.

Mr. Pryor’s mother played the piano for services in a Black church, cooked meals for Black prisoners in a county jail and, at 56, became a missionary among the descendants of slaves in British Guiana. Mr. Clinton’s maternal grandparents, who raised him, ran a small grocery store and during the harsh winters sold goods on credit to people of all races.

Along with another white liberal Democrat, Dale Bumpers, Mr. Pryor and Mr. Clinton courted union members and Black voters. All three won their first primary elections for governor against the same notorious segregationist, former Gov. Orval E. Faubus, who had called out the National Guard in 1957 in a futile effort to block the integration of Little Rock High School.

Attempting comebacks three times, Mr. Faubus lost Democratic primaries to Mr. Bumpers in 1970, Mr. Pryor in 1974 and Mr. Clinton in 1986. In heavily Democratic Arkansas, each man crushed his Republican opponent in the general election. Their governorships became springboards to national prominence — for Mr. Bumpers and Mr. Pryor in the Senate, and for Mr. Clinton in the White House for two terms.

“Senator Bumpers, former Senator David H. Pryor, and Bill Clinton as governor had formed a practically unbeatable triumvirate of elected Democrats in Arkansas for nearly two decades,” The New York Times reported in 1997 as the careers of the three longtime friends and political allies were drawing to a close.

Shortly after he graduated from the University of Arkansas in 1957, Mr. Pryor founded a small weekly newspaper, The Ouachita Citizen, in his hometown, Camden, Ark. During the heyday of the Faubus era, The Citizen was a progressive voice in Southern Arkansas. Mr. Pryor, who served as both editor and publisher, closed the paper after five years, but he kept its progressive ideas alive in his political career.

In 34 years as an elected official, he served in the Arkansas House of Representatives (1961-66), the United States House of Representatives (1966-73), the governorship (1975-79) and the Senate (1979-97). He was an ardent supporter of the aged, labor unions, national health programs, tax reforms, families, farmers, small businesses and environmental causes.

In 1966, after President Lyndon B. Johnson appointed Representative Oren Harris to a federal judgeship, Mr. Pryor won a special election to succeed him in the House. Analysts said he was more liberal than many of his constituents, especially on racial issues, but he was re-elected twice without opposition.

Seeking insights into ways to reform health care for the aged, Mr. Pryor went under cover in 1970 as a volunteer at nursing homes in the Washington region. He made national headlines with disclosures of patients being neglected and abused in filthy, poorly equipped homes run by profit-hungry corporations and callous personnel.

Many nursing homes were “human junkyards,” he said. “No one is protecting the public, no one is protecting the tax dollar and no one is protecting the patient.”

Though little known outside his congressional district, Mr. Pryor was making a name for himself, and in 1972 he challenged the re-election of Arkansas’s senior senator, John L. McClellan, who was seeking a sixth term and was widely regarded as unbeatable. Mr. Pryor’s dynamic style contrasted sharply with Mr. McClellan’s, and while he lost the race, he struck many voters as a politician to watch.

He did not seek a fourth term in the House; instead, he began planning his next step up. After two years of law practice, he entered the race for governor in 1974, clashing with Mr. Faubus in the Democratic primary. Arkansas politics had changed dramatically in the eight years since Mr. Faubus had been governor, particularly in perceptions of race relations. Mr. Pryor narrowly won the primary, and went on to win the general election for a two-year term as governor.

Political observers said Mr. Pryor’s most important accomplishment as governor was his appointment of large numbers of African Americans and women to high-profile state government positions. He also called a constitutional convention to reform state laws and created a new department of natural and cultural heritage to protect the environment and historical sites.

A gregarious campaigner with an engaging personal style, he was often out mingling with his constituents; he traveled around the state to attend meetings, dine in local restaurants and exchange views with voters who stopped to shake his hand, get an autograph, share a reminiscence or tell a story. He was as eager to make contact as they were, and it translated into votes.

After his easy re-election in 1976, he failed to pass his “Arkansas Plan,” a package that sought cuts in state taxes and a sharp increase in local taxing powers. It was a way, he said, to bring the government closer to the people. He held town-hall meetings across the state, but voters and legislators feared that funding for local schools would suffer, and the plan failed.

During his second term as governor, from 1977 to 1979, Mr. Pryor’s attorney general was Mr. Clinton, who won his first term as governor in 1978 when Mr. Pryor moved up to the Senate, taking the seat long held by Mr. McClellan, who had died in 1977.

In the Senate, Mr. Pryor proposed overhauling antitrust laws and favored national health insurance programs. As chairman of the Committee on the Aging, he championed bills to tighten Medicare regulations governing nursing homes and to withhold tax credits from drug companies that raised prices faster than inflation.

Leading a subcommittee on oversight of the Internal Revenue Service, he proposed reforms to shift more taxes to the wealthy and to corporations. In 1988, he wrote the Taxpayer Bill of Rights, which laid out entitlements to fair treatment, privacy, legal representation and challenges to the I.R.S. in legal proceedings. In disputes, it shifted the burden of proof from the taxpayer to the I.R.S.

Late in his career, Mr. Pryor actively supported Mr. Clinton’s campaigns for the presidency in 1992 and 1996 and became an important Senate liaison with the White House on the administration’s legislative agenda.

David Hampton Pryor was born on Aug. 29, 1934, in Camden, Ark., to William Edgar and Susan (Newton) Pryor. His father, a car dealer, and his maternal grandfather were sheriffs in Ouachita County. His mother, a music-shop bookkeeper, was the first Arkansas woman to run for elective office after women won the right to vote in 1920. (She lost a race for County Circuit Court clerk in 1926.)

David and his siblings, William Jr., Cornelia and Elinor, attended public schools in Camden. He graduated from Camden High School in 1952 and attended the University of Arkansas, where he earned a bachelor’s degree in government in 1957 and a law degree in 1964. He entered politics with a successful run for the State Legislature in 1960 and was re-elected in 1962 and 1964.

In 1957, he married Barbara Jean Lunsford. They had three sons. In addition to his son Mark — who was the Arkansas attorney general from 1999 to 2003 and was elected to his father’s old seat in the United States Senate in 2002, serving two terms before losing his re-election bid in 2014 — he is survived by his wife; his other sons, David Jr. and Scott; his sisters, Elinor Pryor and Cornelia Lindsey; four grandchildren; and a great-grandson. His brother, William E. Pryor Jr., died in 1994.

After his political career ended, Mr. Pryor was the founding dean of the University of Arkansas’s Clinton School of Public Service from 2004 to 2006. In 2008, he published his autobiography, “A Pryor Commitment,” written with Don Harrell. That year, after the assassination of State Senator Bill Gwatney, he was appointed interim chairman of the State Democratic Party. In 2009, Gov. Mike Beebe named him a trustee of the University of Arkansas.

He was a board member of the Corporation for Public Broadcasting from 2006 to 2014 and its vice chairman in 2010 and 2011. He received the corporation’s Lifetime Achievement Award in 2019.

Mr. Pryor had a history of medical problems. In 1991, he had a heart attack at his Washington home, and the next year he underwent triple bypass surgery. He had more bypass surgery in 2006 after a heart attack at his home in Little Rock. In 2016, he had a stroke that necessitated surgery, but he recovered.

During the coronavirus pandemic, Mr. Pryor and his wife both tested positive for Covid-19 in July 2020. Because of his age and his medical history, Mr. Pryor was hospitalized for a time in Little Rock; his wife, who was asymptomatic, remained at home.

Mark Pryor said that President Biden had called on Friday to speak with the Pryor family. “They served 18 years together in the Senate,” he said. “The president said the one word he thought of about my father was ‘integrity.’”

Steve Barnes contributed reporting.