NEW YORK — There are few stories about the Kennedy family that could rightly be described as undertold. Maria Shriver thinks she has one. It's about her dad.

California's first lady has produced a documentary about Sargent Shriver, the Kennedy in-law who helped create 1960s era programmes such as the Peace Corps, Head Start and Legal Services for the Poor and was the Democratic vice presidential candidate in 1972.

The film, "American Idealist," debuts to night on PBS (check local listings).

His daughter believes few people remember or are even aware of Shriver's role in American history.

"A lot of people just focused on Uncle Jack or on Uncle Bobby, or they focused on Lyndon Johnson," she told The Associated Press. "There wasn't a lot of media for the quote-unquote second-tier players."

Uncle Jack, of course, was President John F. Kennedy. Uncle Bobby was Sen. Robert F. Kennedy. Shriver married their sister, Eunice, in 1953. He was a classic 1960s liberal, maybe the perfect embodiment of a political creature largely lost to history.

Shriver is still alive today, 92 and under the shroud of Alzheimer's disease. He's in a Washington area health-care facility, unable to recognise the family he loved.

He grew up in Maryland, the son of a stockbroker ruined in the Depression. His strong-willed mother converted his father from a Republican to a Democrat, an effort his daughter has been unable to repeat with her husband, California Gov. Arnold Schwarzenegger.

After marrying Eunice, Shriver established himself in Chicago business and politics. He was contemplating a run for governor of Illinois when family duty beckoned with John F. Kennedy's 1960 presidential candidacy.

Among the behind-the-scenes stories captured in "American Idealist" is when Shriver persuaded Kennedy to reach out to Martin Luther King when he was jailed in Alabama. The simple step helped cement the black vote for Kennedy in one of the nation's closest presidential races. The documentary makers interview Coretta Scott King, who received Kennedy's phone call.

Kennedy asked Shriver to run the Peace Corps, an organisation the president didn't expect much from. But it was wildly successful, tapping into a burst of youthful idealism.

Following Kennedy's assassination — Jackie asked Shriver to organise the funeral — he stayed on under the Johnson administration and was asked to run the War on Poverty. The film airs fascinating audiotapes of a reluctant Shriver talking about the job with Johnson, who uses his legendary power of persuasion to enlist the Kennedy in-law.

"It's easy to dismiss him as an in-law and somebody who ran (for president in 1976) and didn't win, but I think he was unbelievably successful and had an incredible impact," his daughter said. "All of these programmes still exist and they still change people's lives."

Shriver's anti-poverty efforts became bogged down in battles with local politicians and Johnson's need to pour money into the Vietnam War. He accepted Johnson's offer to become ambassador to France in 1968.

While being in the Kennedy family helped put Shriver into important government roles, it thwarted his political ambitions. He was considered as a running mate by both Johnson in 1964 and Hubert Humphrey in 1968, but resistance from the Kennedy circle took him out of the running. He joined George McGovern's sinking-ship campaign in 1972 after McGovern's first choice of a running mate was forced to withdraw.

One of his few hints of frustration was seen when the film quoted a letter from Shriver to a friend talking about "the palace guard without the palace."

Maria Shriver, 52, said it wasn't a topic that she ever talked about with her father.

"He was not a complainer," she said. "There isn't another family in the country where four people ran for president from the same family. Imagine if four people were trying to be doctors at the same hospital from one family."

Much of Sargent Shriver's later years were spent with the Special Olympics, an organisation that began when Eunice invited mentally disabled youngsters for some athletic competition in their backyard in Maryland.

"American Idealist" is an outgrowth of a recent biography. The book was meant to be an autobiography, but the onset of disease prevented Shriver from finishing it. Maria Shriver said the film was made so his story could reach more people.

It's the kind of journalism most likely to be in her future. The former "Dateline NBC" reporter went on extended leave from NBC News when her husband ran for governor in 2003. She said last year that the media circus surrounding Anna Nicole Smith's death last year persuaded her to call NBC and say she wasn't coming back.

"I love journalism," she said. "I love the possibility that good journalism can inspire people and educate people if done well. I think there are many opportunities to do certain forms of journalism."

The documentary will have hit its mark if young people watch and realise there are ways to perform public service without running for office, she said. She hopes young people ask presidential candidates to emphasise public service — that, and for increased funding of research into Alzheimer's disease.