Former senator Mark O. Hatfield of Oregon, whose liberal Republican politics during five terms in Congress made him an increasingly rare breed in his party, and who used his chairmanship of the Appropriations Committee to denounce what he considered the “madness” of excessive defense spending, died Aug. 7 at a care facility in Portland.

He was 89. He had congestive heart failure, among other ailments, said his son Mark Jr.

As a Navy officer during World War II, Mr. Hatfield saw the devastation wrought by atomic warfare in the Japanese city of Hiroshima. That experience, coupled with his Baptist faith, was a defining force in shaping Mr. Hatfield’s political views during nearly half a century in elected office.

He became an opponent of abortion, the death penalty and war — a “consistently pro-life” politician, said Oregon political scientist Bill Lunch, “who took the religious injunction not to do harm to others seriously.”

During his three decades on Capitol Hill, Mr. Hatfield was one of the Senate’s most unwavering pacifists. He joined George S. McGovern (D-S.D.) in sponsoring a 1970 amendment to bring U.S. troops home from Vietnam; spearheaded an effort with Sen. Edward M. Kennedy (D-Mass.) to freeze the nuclear arms race; and, in 1990, was one of only two Republican senators (the other was Charles E. Grassley of Iowa) to vote against going to war in the Persian Gulf.

When Mr. Hatfield announced his retirement in the mid-1990s, he used the occasion to criticize President Bill Clinton’s plan to send U.S. forces to intervene in Bosnia’s civil war. “I do not believe we can solve 800 years of history by sending our troops over there,” he said.

Mr. Hatfield never voted for a military authorization bill. As head of appropriations from 1981 to 1987, he was one of the most powerful dissenters against President Ronald Reagan’s political agenda. He redirected money from Reagan’s Pentagon budget to social safety-net programs and urged Democrats to join him in fighting the “Star Wars” program.

“There is to me a direct ratio between the increase of our arsenals and the diminishing sense of national security,” he told the Christian Science Monitor in 1982.

“There comes a time in a nation’s life when additional money spent for rockets and bombs, far from strengthening national security, will actually weaken national security — when there are people who are hungry and not fed, people who are cold and not clothed.”

Mr. Hatfield, a critic of extremism across the political spectrum, carved a centrist path on divisive issues such as the environment. An early supporter of the Endangered Species Act and federally protected wilderness, he later drew the scorn of preservationists for defending the logging industry during the bitter timber wars of the 1980s and ’90s.

His voting record played well in Oregon, a state with left-leaning cities and conservative rural communities. His popularity was boosted by his seniority in Washington and his ability to funnel billions of dollars to Oregon for hospitals, transportation infrastructure and higher education.

Mr. Hatfield was known to Senate colleagues as “Saint Mark” for his pacifism and teetotaling gentility, but his record was far more complicated than the nickname suggested.

In the 1980s, his wife accepted $55,000 in payments for real estate work from a business tycoon with a multibillion-dollar contract before Congress. Mr. Hatfield apologized for the appearance of wrongdoing and gave the money to charity.

Several years later, in 1992, he was formally rebuked by the Senate ethics committee for not disclosing more than $42,000 in gifts from friends and lobbyists — the result of a “careless” clerical error, he said at the time.

Mr. Hatfield, protected by the respect he had built on both sides of the aisle, emerged from the scandal only lightly bruised, his reputation largely intact.

As the GOP tilted right under the growing influence of social conservatives, however, he found himself increasingly isolated in his own party.

He was reinstalled as chief of appropriations after Republicans recaptured the Senate majority in 1994, but the landscape had shifted. His deciding vote in 1995 against a balanced-budget amendment, which had been a key Republican aim for months, triggered a mutiny among conservative freshmen such as Sen. Rick Santorum (Pa.), who tried unsuccessfully to strip Mr. Hatfield of his chairmanship.

Mr. Hatfield, who said he thought the amendment would have starved social programs of federal money, shrugged off the anger. “I’ve been out of step most of my political life,” he said. “What else is new?”

The feud was just one sign of Washington’s increasing polarization. Facing conservatives in Oregon who threatened to mount a serious primary challenge, Mr. Hatfield declined to run for reelection in 1996.

He was one of 13 senators who retired in 1997. Many of those who left office, including Sam Nunn (D-Ga.) and William S. Cohen (R-Maine), were known for voting across party lines. It was the biggest exodus from the Senate in more than a century.

Mark Odom Hatfield was born July 12, 1922, in the western Oregon mill town of Dallas. His father was a railroad blacksmith and a Democrat, but it was his mother’s politics that prevailed. A schoolteacher and Republican, she campaigned for President Herbert Hoover’s reelection with her son in tow.

Mr. Hatfield attended Willamette University in Salem, Oregon’s capital, where he ran for student president and suffered the sole political defeat of his career. After graduating in 1943, he joined the Navy and participated in the battles of Iwo Jima and Okinawa before sailing into Hiroshima’s harbor after the end of World War II.

“If you’ve been in a war, you cannot but have your views altered,” he told the Associated Press in 1986. “The devastation, the terrible devastation, is not something one ever forgets.”

After the war, he received a master’s degree in political science at Stanford University and began a political career in Oregon. First elected to the legislature in 1950, he was instrumental in passing measures banning racial discrimination in housing and public accommodations in his first few years in office — a decade before the government considered similar civil rights laws.

In 1958, he won the governorship, becoming the state’s youngest-ever chief executive. The same year, he married Antoinette Kuzmanich.

In addition to his wife, of Portland, survivors include their four children, Dr. Elizabeth Hatfield-Keller of Portland, Mark O. Hatfield Jr. of Coral Gables, Fla., Theresa Cooney of Potomac and Charles “Visko” Hatfield of Bantam, Conn.; and seven grandchildren. A grandson, Mark, a former Marine Corps corporal who served in Iraq, died a few weeks ago.

Oregon’s economy soared under Mr. Hatfield’s leadership as he courted trading partners in Asia and enticed technology, health care and other industries to the state. He won a second term and was seen as a rising national GOP star who was chosen to nominate then-Vice President Richard M. Nixon at the 1960 Republican National Convention. He gave the convention’s keynote address four years later.

Despite his widespread popularity, Mr. Hatfield nearly lost his first race for U.S. Senate, in 1966, against Robert Duncan, a hawkish Democratic congressman. At a time when three-quarters of Oregonians said they supported the war in Vietnam, Mr. Hatfield fell behind in the polls, and observers predicted that his dovish views were driving away voters.

Mr. Hatfield stuck to his position, saying, “You can’t stop communism with bullets.” Emphasizing Johnson administration policies that he said were bruising the Oregon timber industry, Mr. Hatfield eked out a narrow victory.

Two years later, he emerged as a likely running mate for presidential candidate Nixon. The Miami Herald even printed a story during the Republican National Convention in Miami declaring Mr. Hatfield the vice presidential nominee.

Mr. Hatfield had the strong support of evangelical leader Billy Graham, but his civil rights record and pacifism brought immediate opposition from Southern Republicans such as Sen. Strom Thurmond of South Carolina. At the last moment, Nixon chose Maryland Gov. Spiro T. Agnew as his running mate.

Mr. Hatfield said he never talked to Nixon or Graham about being passed over. He spoke to reporters, congratulated Agnew and went to the beach for a swim.

He went on to document the tensions between his convictions and his party in books such as “Between a Rock and a Hard Place” (1971) and “Against the Grain: Reflections of a Rebel Republican” (2001).

While in the Senate, he helped pass a ban on underground nuclear tests. He campaigned for rules to prohibit the sale of arms to undemocratic countries and countries that do not respect human rights.

As he left office, he spoke bluntly about the regrets he felt about the work he left unfinished. “We’re still the largest arms peddler in the world,” he said in 1997, “and we infect the rest of the world with our lust for weapons.”