George S. McGovern, the three-term senator from South Dakota who carried the Democratic Party’s liberal banner in the Vietnam War era, launched a star-crossed bid for the presidency in 1972, and energized many of the leading Democrats of the past generation, died Sunday at a hospice in Sioux Falls, S.D. He was 90.

In a public career spanning more than five decades, Sen. McGovern may be best remembered for a presidential campaign of near-epic futility, in which he lost 49 of 50 states. The senator’s liberal agenda — supporting civil rights and anti-poverty programs and strongly denouncing the Vietnam War — were critical to his landslide defeat to President Richard M. Nixon. But those views also helped define the future vision of the Democratic Party.

“In many ways, he revolutionized the Democratic Party,” said Ross K. Baker, a Rutgers University political science professor and an authority on congressional politics. “His followers drove out the old guard. . . . Some would say it was the end of the old Democrats, but others would say, no, it opened up the party to women and others.”

Family spokesman Steve Hildebrand confirmed Sen. McGovern’s death to the Associated Press. The cause was not disclosed.

Among those who worked on his 1972 campaign were Bill Clinton, a future governor and president; Hillary Rodham Clinton, a future senator and secretary of state; and Gary Hart, a future senator and presidential candidate. Political consultant Robert Shrum and Washington lobbyist Gerald Cassidy also gained experience working for Sen. McGovern, as did future national security adviser Samuel R. Berger and future White House chief of staff John D. Podesta.

“George McGovern dedicated his life to serving the country he loved,” President Obama said Sunday in a statement. “He signed up to fight in World War II and became a decorated bomber pilot over the battlefields of Europe. When the people of South Dakota sent him to Washington, this hero of war became a champion for peace. And after his career in Congress, he became a leading voice in the fight against hunger. George was a statesman of great conscience and conviction, and Michelle and I share our thoughts and prayers with his family.”

Sen. McGovern, a minister’s son, was raised in a South Dakota farm community during the Depression and served in World War II. Both experiences — seeing people asking for food at his family’s doorstep and witnessing emaciated child beggars in wartime Italy — molded his political career from the moment he was elected to Congress in 1956.

In the early 1960s, he conceived the idea of the U.S. Food for Peace program, which gave foreign nations credit to buy surplus U.S. crops, and served under President John F. Kennedy as the program’s first director. In that position, he played a central role building the United Nations’ World Food Program, a humanitarian organization that has provided food assistance to hundreds of millions of victims of wars and natural disasters.

After winning his Senate seat in 1962, he spent much of his public life working on the expansion of food stamp and school lunch programs and championing civil rights and the Nuclear Test Ban Treaty in the Senate. After being defeated for reelection to the Senate in 1980, he served as the U.S. representative to the U.N. Food and Agricultural Organization in Rome and as a U.N. global ambassador on world hunger.

“It is in our self-interest to end hunger,” he wrote in a 1998 editorial published in the Los Angeles Times. “After all, we live in one world. Rich and poor alike, we breathe the same air; we share a global economy. . . . The chaos associated with political instability rooted in poverty and desperation is rarely contained within a single country.”

As part of his wide-ranging humanitarian interests, Sen. McGovern was synonymous with the antiwar movement. In September 1963, he became the first person to challenge the burgeoning Vietnam War on the Senate floor, with five paragraphs tucked into a speech about disarmament.

But Sen. McGovern voted for the Tonkin Gulf Resolution in 1964, giving President Lyndon B. Johnson almost blank-check authority to escalate the war. By the next year, Sen. McGovern joined a small group of senators who called U.S. involvement in Vietnam a mistake.

“We are fighting a determined army of guerrillas that seems to enjoy the cooperation of the countryside and that grow[s] stronger in the face of foreign intervention,” he said in a widely noticed Jan. 15, 1965, Senate speech that marked him as the leading Senate pacifist. “We are further away from victory over the guerrilla forces in Vietnam today than we were a decade ago.” He then laid out a five-point program for withdrawal from the war.

Later that year, he traveled to Vietnam and, between briefings, saw the coffins and the maimed soldiers in military hospitals. The former war hero declared himself sickened, and upon his return home he continued to speak out.

Allard Lowenstein, the organizer of a dump-LBJ movement, asked Sen. McGovern to challenge Johnson in the 1968 presidential primaries, but he refused. After Johnson unexpectedly withdrew, Sen. Eugene McCarthy (D-Minn.) battled incumbent Vice President Hubert H. Humphrey and a late entry, Sen. Robert F. Kennedy (D-N.Y.), until Kennedy’s assassination on June 5, 1968.

Sen. McGovern, who had been a Kennedy supporter, got into the race shortly before the party’s tumultuous Chicago convention, but his 18-day campaign made little splash. Humphrey received the Democratic nomination, and Nixon won the general election.

With Sen. Mark O. Hatfield (R-Ore.), Sen. McGovern proposed an end to the Vietnam War by Dec. 31, 1971. The McGovern-
Hatfield Amendment failed on a 55 to 39 Senate vote in 1970, but millions of Americans embraced Sen. McGovern as a prophet; millions of others considered him a traitor.

“Every senator in this chamber is partly responsible for sending 50,000 young Americans to an early grave,” he scolded his colleagues before the vote. “This chamber reeks of blood.”

Road to nomination

After being reelected to the Senate in 1968, Sen. McGovern led a commission to overhaul the Democratic Party’s nominating process. The result was that candidates could gain the nomination only by winning delegates in contested primary elections, rather than by making deals with statehouse and big-city pols.

The experience proved crucial; Sen. McGovern entered the 1972 presidential race knowing the rules better than anyone else.

He launched his campaign with a letter to 200,000 supporters asking for donations. He campaigned on a pledge to immediately withdraw all U.S. troops from Vietnam and to cut the Pentagon’s budget by 40 percent.

His underdog primary campaign vanquished numerous competitors, including onetime front-runner Sen. Edmund S. Muskie of Maine and conservative Alabama Gov. George Wallace. After Wallace was paralyzed in an attempted assassination while on the campaign trail in Laurel, the former governor withdrew from the Democratic primaries and much of his support went to Nixon in the general election.

Sen. McGovern’s liberal stances were a handicap against the Republican incumbent. Sen. McGovern urged diplomatic recognition of Cuba and China and pledged to decriminalize marijuana, offer amnesty for draft evaders, raise corporate taxes and guarantee a minimum national income. He was blamed for turning the Democratic Party away from the working class and toward the embrace of minorities, women, the gay community and other practitioners of “identity politics.”

The race against Nixon was seen by most as a sure loss. The revelations of the Nixon administration’s involvement in the Watergate scandal — which stemmed from a 1972 break-in at the Democratic National Committee headquarters — had not yet sunk into the public’s consciousness.

During the 1972 Democratic National Convention, Sen. McGovern lost a critical opportunity to reach millions of television viewers when a chaotic floor fight delayed his acceptance speech until nearly 3 a.m.

He offered the vice presidential slot to several prominent Democratic lawmakers, but he was turned down. When Sen. Thomas F. Eagleton of Missouri accepted the No. 2 position, Sen. McGovern said he backed him “a thousand percent.”

Within two weeks, Eagleton stepped down amid revelations that he had undergone psychiatric treatment.

Sen. McGovern replaced Eagleton with R. Sargent Shriver Jr., the Kennedy in-law who was founding director of the Peace Corps and U.S. ambassador to France. But the campaign never recovered.

“I wish I had stayed with my initial judgment to keep Tom” on the ticket, Sen. McGovern told The Washington Post in 2005. “I could have stood up for him had I known more about mental illness at the time.”

The McGovern-Shriver ticket received only 38 percent of the popular vote, carrying just Massachusetts and the District of Columbia, for 17 electoral votes. Nixon won 520 electoral votes.

At the 1973 Gridiron Club dinner in Washington, Sen. McGovern was able to joke, “Ever since I was a young man I wanted to run for the presidency in the worst possible way — and I did.” But the defeat hurt for a long time.

Twelve years later, after Walter F. Mondale, a former Democratic senator from Minnesota and vice president under Jimmy Carter, was beaten by incumbent Ronald Reagan in the 1984 presidential election, he asked Sen. McGovern how long it would take to get over the pain of losing in a landslide.

“I'll let you know when I get there,” Sen. McGovern said.

Decorated war veteran

George Stanley McGovern, the son of a Wesleyan Methodist minister, was born July 19, 1922, in Avon, S.D., and grew up in Mitchell, S.D. He left Dakota Wesleyan University to serve as an Army Air Forces B-24 bomber pilot during World War II. He flew 35 missions over Europe, with his exploits described in Stephen E. Ambrose’s “The Wild Blue” (2001). He received the Distinguished Flying Cross and several Air Medals.

After the war, Sen. McGovern graduated from Dakota Wesleyan in 1946. Torn between the ministry and the study of history, he attended the old Garrett Theological Seminaryin Evanston, Ill., for one year before transferring to Northwestern University, where he received a master's degree in 1950 and a doctorate in 1953, both in American history.

He returned to South Dakota to teach history and government at Dakota Wesleyan. He had been a delegate to the Progressive Party convention in 1948, but he found its politics too radical. Given the chance to become executive secretary of South Dakota’s moribund Democratic Party, he created a base for two successful runs for the U.S. House of Representatives, beginning in 1956.

After his first bid for a U.S. Senate seat failed in 1960, he joined the new Kennedy administration and began his work on alleviating hunger. In 1962, he was elected to the Senate from South Dakota by 597 votes, a rare win by a liberal Democrat in a heavily Republican state.

Exile and influence

After Sen. McGovern’s overwhelming loss in the 1972 election, Democrats lost three of the next four presidential contests. That prompted the centrist Democratic Leadership Council to urge the party’s subsequent nominees to avoid “McGovernism,” which it defined as far-left stances that were out of sync with Middle America. By 1992, Bill Clinton was elected president on a moderate platform that steered away from hard-left positions.

Sen. McGovern won reelection to the Senate in 1974 but was targeted for defeat by Republicans in 1980 and lost by a wide margin to then-Rep. James Abdnor. Angered by the political attacks, Sen. McGovern founded the political interest group Americans for Common Sense in 1981. He launched a brief presidential bid for the 1984 nomination, promoting a national health-care system and reductions in the military budget, but he ended his bid after losses in the early primaries.

He served as president of the Middle East Policy Council from 1991 to 1998, after which President Clinton appointed him representative to the U.N. Food and Agriculture Organization in Rome.

In 2000, Clinton awarded him the Presidential Medal of Freedom, the country’s highest civilian honor. At the ceremony, Clinton called Sen. McGovern “not only a hero in war but a stalwart voice for peace in Vietnam. . . . For decades, his conviction never wavered, nor has his early commitment to bringing food to the hungry.”

In 2001, Sen. McGovern was appointed the first U.N. global ambassador on hunger and published “The Third Freedom: Ending Hunger in Our Time,” in which he proposed a plan to alleviate world hunger by 2030. In 2008, he and former senator Robert J. Dole (R-Kan.) shared a $250,000 award from the World Food Prize Foundation for their work combating hunger among children.

Sen. McGovern wrote more than a dozen books, including a biography of President Abraham Lincoln, published in 2009.

The George and Eleanor McGovern Center for Leadership and Public Service at Dakota Wesleyan University is named for him and his wife of 63 years, the former Eleanor Stegeberg, who died in 2007 at 85.

One of their daughters, Teresa McGovern, an alcoholic, collapsed and froze to death in 1994 in the snow near Madison, Wis. She was 45. The family’s efforts to cope became the subject of one of Sen. McGovern’s books, “Terry: My Daughter’s Life-and-Death Struggle With Alcoholism.”

In The Washington Post, reviewer Carolyn See likened the book to William Styron’s classic “Lie Down in Darkness” for its “brooding inevitability” as it details the story of “a precariously stable family trying to hold on to a child who — because of drugs, drink, depression — cannot be held on to, and who sinks away, into some form of oblivion.”

Sen. McGovern’s son, Steven McGovern, died in July. At the time, Sen. McGovern’s daughter Ann said her brother had had “a long struggle with alcoholism.”

Survivors include three daughters, Ann, Susan and Mary; and several grandchildren and great-grandchildren.

Sen. McGovern was often asked to reflect on the significance of his ill-fated 1972 race. He said it was notable for motivating and training a generation of young Democrats who became the party’s future leaders.

“For the last 25 years,” he told the Dallas Morning News in 1998, “I’ve been running into mayors and state legislators and city council people and governors and others who say that that was where they got their first real fire for politics.”