Massachusetts Sen. Edward M. Kennedy has died after a yearlong battle with a brain tumor

BOSTON (AP) - Sen. Edward Kennedy has died after a long battle with a brain tumor. He was 77.

The youngest of the Kennedy brothers, he became perhaps the most powerful liberal voice in the U.S. Senate of his time.

Kennedy was diagnosed with a malignant brain tumor in May 2008 after suffering a seizure at his Massachusetts home. He underwent an aggressive and delicate surgery in early June at Duke University Medical Center in North Carolina. Doctors removed as much of the tumor as possible and he underwent a grueling regimen of radiation and chemotherapy.

Kennedy was heir to America's most potent and glamorous political family of the 20th century. His endorsement, along with the backing of other family members, gave Barack Obama's Democratic presidential candidacy a major boost in the midst of the 2008 primary season.