Word of Kennedy's death came early today, prompting an outpouring of praise lauding the brother of assassinated President John F. Kennedy and presidential contender and former Attorney General Robert F. Kennedy as one of the most influential politicians of the last century.
President Obama said in a statement that he and first lady Michelle Obama were "heartbroken" to learn of Kennedy's death, calling the Democratic senator "our dear friend."
"An important chapter in our history has come to an end. Our country has lost a great leader, who picked up the torch of his fallen brothers and became the greatest United States senator of our time," Obama said in a written statement.
Obama interrupted his vacation at Martha's Vineyard today to make a public statement in which he called Kennedy, "one of the most accomplished Americans ever to serve this democracy."
The president said legislation Kennedy fought for affected millions of Americans, "including myself."
In one of the many dramatic moments of his long career, Kennedy came out late in the bruising 2008 Democratic presidential primary and endorsed Obama over Sen. Hillary Clinton, D-N.Y., with a roaring speech that typified the last "liberal lion" of the Senate.
"The torch will be passed again to a new generation of Americans," he declared, invoking echoes of the Kennedy family's golden years of Camelot.
A few hours after Kennedy died, the family issued a statement that said, "We've lost the irreplaceable center 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."
Kennedy had battled his brain cancer since first being diagnosed last May, remaining active up to his final days. He strategized with Obama and Connecticut Sen. Chris Dodd on the health care reform bill, and even pressing for a new law in Massachusetts that would allow the governor to quickly appoint a successor instead of waitiing for a special election.
Sen. Robert Byrd, a Democrat from West Virginia, praised his longtime friend and said any healthcare bill should be named in his honor.
"I had hoped and prayed that this day would never come. My heart and soul weeps at the lost of my best friend in the Senate, my beloved friend, Ted Kennedy," Byrd, the longest serving senator in history, said of Kennedy, the third-longest serving senator.
ABC News' Dr. Tim Johnson said Kennedy had the worst kind of brain cancer, but he "outlived his prognosis by a few months." Johnson said Kennedy "died gradually over a few days."
The family had hoped that Kennedy would live long enough to see health care reform passed and to see his memoir come out in October, according to ABC News' Senior Washington Correspondent George Stephanopoulos.
The last time Kennedy was seen in public was on Aug. 3, when he was wheeled out for a final sailing trip on the waters off his beloved Cape Cod.
"He was a quite extraordinary person," Bob Shrum, a lifelong friend and former Kennedy press secretary, told ABC's "Good Morning America" today. "He had an indomitable spirit that really saw him through this illness and made him perhaps the greatest senator of the last 100 years."