Washington, Aug 26 (DPA) US Senator Edward 'Ted' Kennedy, the liberal lion hailed as one of the country's most effective lawmakers ever and the first important Democrat to challenge President George W. Bush over the Iraq war, died of brain cancer late Tuesday. He was 77.

After seeing two high profile brothers, including a president, assassinated in the 1960s, Kennedy served as a senator since 1962, and is credited with pushing through major milestones in social, civil and voting rights legislation that protected the disenfranchised and advocated for the elderly, disabled, immigrants and workers.

But despite his popularity and high standing, the White House always remained out of reach. Kennedy's reputation as a party reveller and the scandal known as Chappaquiddick always stood between him and the presidency.

The revelation in May 2008 that he had a serious form of brain cancer sent tears and a stunned silence across the US Congress, where his laughter, kidding and consistent interest in the personal welfare of his colleagues once dominated the corridors.

Outside medical experts expressed sobering prospects for recovery from the malignant glioma tumour in the then-76-year-old senator's left parietal lobe.

But many of Kennedy's colleagues were upbeat, believing that the man who fought so hard for legislation would overcome this challenge, too.

'He's a strong guy, with a great heart,' said Senator Chris Dodd, a fellow Democrat from Connecticut, a neighbouring state to Kennedy's native Massachusetts.

US President Barack Obama, the country's first president who received a strong, early endorsement from Kennedy, said after learning of his illness in 2008 that he 'would not be sitting here as a presidential candidate had it not been for the battles Ted Kennedy has fought.'

'I stand on his shoulders,' Obama said.

Edward Moore 'Ted' Kennedy, born Feb 22, 1932, in Brookline, Massachusetts, was the youngest of nine children born to Joseph and Rose Kennedy. The family is recognised as one of the oldest, richest and most influential families in the US.

His death followed shortly after that of his older sister Eunice, who died at age 88 Aug 11. The only surviving sibling of the Camelot Kennedy generation is Jean, 81, a former US Ambassador to Ireland.

After studying law at Harvard University, Ted Kennedy went rapidly into politics and was elected to the US Senate in 1962, where he took the seat vacated by his brother, President John F. Kennedy, who had entered the White House in 1961.

Viewed in the context of history, Ted Kennedy had more influence on US politics than either of his famous brothers. President Kennedy was assassinated in the third year of his presidency in 1963. Robert Kennedy, who served as JFK's attorney general, was shot dead while campaigning for the presidency in the tumultuous year of 1968 that also saw civil rights hero Martin Luther King assassinated.

The oldest of the Kennedy siblings, Joseph, was a pilot killed in World War II.