Joseph P. Kennedy and his wife, Rosemary Kennedy, pose with their nine children in 1938. Seated from left: Eunice, Jean, Edward (on lap of his father), Patricia and Kathleen. Standing from left: Rosemary, Robert, John, Mrs. Kennedy, and Joseph Jr. (Boston Globe, File/Associated Press)The last brother of the Kennedy political dynasty, U.S. Senator Edward Kennedy, died late Tuesday night after a year-long battle with brain cancer.

Kennedy, known as Ted to his family and friends, died at his home in Hyannis Port, Mass., his family announced in a statement early Wednesday. He was 77.

The Massachusetts senator will be buried at Arlington National Cemetery, where his slain brothers, former U.S. president John F. Kennedy and Senator Robert Kennedy, are also buried, according to media reports.

He will lie in repose on Friday, and his funeral service is set for Saturday, an Obama administration official told Reuters. A source told The Associated Press that Obama will eulogize Kennedy at his funeral mass.

"We've lost the irreplaceable centre of our family and joyous light in our lives, but the inspiration of his faith, optimism, and perseverance will live on in our hearts forever," the family statement said.

"We thank everyone who gave him care and support over this last year, and everyone who stood with him for so many years in his tireless march for progress toward justice, fairness and opportunity for all."

Kennedy was diagnosed with a cancerous brain tumor in May 2008. He underwent surgery and a gruelling regimen of radiation and chemotherapy.

Kennedy's son, Rhode Island Democratic congressman Patrick Kennedy, told The Associated Press recently that his father had defied doctors' predictions that he would not survive more than a year after his diagnosis.

His death comes just weeks after that of his sister, Eunice Kennedy Shriver, 88, on Aug. 11.

California Gov. Arnold Schwarzenegger, who is married to Kennedy's niece Maria Shriver, issued a statement on Wednesday morning saying that Kennedy was "the rock of our family."

"Teddy taught us all that public service isn't a hobby or even an occupation, but a way of life and his legacy will live on," Schwarzenegger said.

Kennedy was first elected to the U.S. Senate in 1962, when his brother, John F. Kennedy, was president.

Liberal lion

Known as the liberal lion of the U.S. Senate, Kennedy was the third longest serving senator in American history, serving almost 47 years. He was a steadfast champion of the working class and the poor and known as a powerful voice on health care, civil rights, war and peace.

In his last known public appearance in early August, Senator Edward Kennedy arrives at the home of his sister Eunice Kennedy Shriver, who died Aug. 11 at the age of 88. (Steven Senne/Associated Press)U.S. President Barack Obama took a break from his family vacation on the Massachusetts island of Martha's Vineyard to hold a press conference Wednesday morning at which he paid tribute to Kennedy.

Obama called Kennedy a "singular figure in American history."

"His ideas and ideals are stamped on scores of laws and reflected in millions of lives," Obama said.

Obama, who received Kennedy's endorsement in the 2008 Democratic primary, said in an earlier written statement he was "heartbroken" by the news of the death and also thanked Kennedy for "his wise counsel in the Senate" and his support in the presidential race.

Known as a consummate congressional dealmaker and one of the most effective senators, Kennedy authored more than 2,500 bills during his time in office. His legislative achievements included bills to provide health insurance for children of the working poor, the landmark 1990 Americans with Disabilities Act, Meals on Wheels for the elderly, abortion clinic access, family leave and the Occupational Safety and Health Administration.

U.S. Senator Ted Kennedy, shown in April 2009, died on Tuesday night after a battle with brain cancer. (Jason Reed/Reuters)He was also a key negotiator on legislation creating a Medicare prescription drug benefit for senior citizens and was a driving force for peace in Ireland and a persistent critic of the war in Iraq.

Kennedy always maintained that there was more work to be done to improve life for American citizens.

"There's a lot to do," Kennedy said in a 2006 interview. "I think most of all it's the injustice that I continue to see and the opportunity to have some impact on it."

Kennedy fought his way back to Capitol Hill during the summer of 2008 to cast a pivotal vote for the Democrats on Medicare. He made sure he was there again last January to see Obama sworn in as the nation's first black president, only to collapse in fatigue at a celebratory luncheon afterward.

Although Kennedy had been sidelined since his cancer diagnosis, and often looked tired and drained when he appeared at work with his cane, staff and colleagues maintained that he was to determined to fulfil what he called his "cause" of seeing health insurance provided to all Americans.

"I've benefited from the best of medicine, but I've also witnessed the frustration and outrage of patients and doctors alike as they face the challenges of a system that shortchanges millions of Americans," he wrote in a May 28, 2009, issue of the Boston Globe.

Youngest child

Kennedy, born in 1932 and the youngest of nine children, was also known to the American public as the last surviving son of the glamorous political family. He was the only one of the four Kennedy brothers to die of natural causes.

Senator Edward M. Kennedy, centre, poses with his brothers U. S. Attorney General Robert F. Kennedy, left, and President John F. Kennedy at the White House in Washington in 1962. (Associated Press)Kennedy's eldest brother, Joseph, was killed in a plane crash in the Second World War. John F. Kennedy was assassinated in Dallas in 1963. Senator Robert F. Kennedy was gunned down in Los Angeles as he campaigned for the 1968 Democratic presidential nomination.

"I think about my brothers every day," Kennedy said. "They set high standards. Sometimes you measure up, sometimes you don't."

Kennedy's hopes of reaching the White House in 1980 — when he sought the party's nomination against sitting president Jimmy Carter — were damaged by the 1969 Chappaquiddick incident when Kennedy drove a car off a bridge on Martha's Vineyard and left the other passenger, a 28-year-old woman, dead in the submerged vehicle. He pleaded guilty to leaving the scene and received a suspended sentence.

His presidential ambitions thwarted, Kennedy devoted himself to his senate career.

Carter said that despite the tough and divisive primary campaign, the two had long ago reconciled their political rivalry and had a good working relationship on a number of issues.

“I have called on Ted Kennedy as a friend and he's always been fully supportive. Those political skirmishes were soon forgotten and the friendship prevailed,” Carter told CNN.

Kennedy married Virginia Joan Bennett, known as Joan, in 1958. They divorced in 1982. In 1992, he married Washington lawyer Victoria Reggie. His survivors include a daughter, Kara Kennedy Allen; two sons, Edward Jr. and Patrick; and two stepchildren, Caroline and Curran Raclin.

Tragedies dogged Kennedy throughout his life, including a 1964 plane crash that damaged his spine and left him with lifelong pain, his son's battle with bone cancer and his first wife's alcoholism and drug problems.

For years, Kennedy himself was plagued by accusations of alcoholism and womanizing, the tales of his behaviour making him a regular political punchline.

His reputation also suffered after his nephew William Kennedy Smith was accused of raping a woman in 1991. Smith had met the woman at a Florida nightclub while out for a night of drinking with Kennedy and Kennedy's son Patrick.

His nephew was acquitted of the charge.

Shortly before the trial, during a speech at the Institute of Politics at Harvard University's John F. Kennedy School of Government, Kennedy said he recognized his "own shortcomings — the faults in the conduct of my private life. I realize that I alone am responsible for them, and I am the one who must confront them."

His second marriage to Reggie was also credited for bringing stability to his personal life.

Jean Kennedy Smith is now the sole surviving child of Joseph Kennedy, a millionaire businessman and former U.S. ambassador to Britain, and his wife, Rose.

Under state law, Kennedy's successor will be chosen by special election within 160 days. In his last known public act, the senator urged state officials to give Democratic Gov. Deval Patrick the power to name an interim replacement.

With files from The Associated Press