VIDEO: President Obama: Ted Kennedy Was The "Greatest US Senator Of Our Time"

Tributes Wednesday poured in for Senator Ted Kennedy, the longtime Massachusetts senator who died Tuesday night at 77 after battling brain cancer for a year.

"An important chapter in our history has come to an end," President Barack Obama, vacationing at Martha's Vineyard, said Wednesday. "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 learned of Kennedy's death shortly after 2 a.m. Wednesday, and talked to the senator's widow, Victoria, around 2:25 a.m, according to a White House official.

Obama credited Kennedy -- the second-longest serving senator of all-time, whose tenure overlapped nine presidents and 10 senators -- for personally supporting him in both his bid for the White House, as well as once he got there.

"I cherished his confidence and momentous support in my race for the presidency," Obama said. "Even as he waged a valiant struggle with a mortal illness, I've profited as president from his encouragement and wisdom."

Also chiming in with words of wisdom was former first lady Nancy Reagan, who issued a statement lauding Kennedy’s relationship with her late husband, former President Ronald Reagan.

"Given our political differences, people are sometimes surprised by how close Ronnie and I have been to the Kennedy family,” she said. “But Ronnie and Ted could always find common ground, and they had great respect for one another. In recent years, Ted and I found our common ground in stem cell research, and I considered him an ally and a dear friend. I will miss him."

California Gov. Arnold Schwarzenegger, related to Kennedy by his marriage to Maria Shriver, praised him for his work in the senate and at home.

"He was known to the world as the Lion of the Senate, a champion of social justice, and a political icon,” Schwarzenegger said. “Most importantly, he was the rock of our family: a loving husband, father, brother and uncle."

Kennedy’s career was marked by a series of triumphs and tragedies: the weathered leader held strong as both of his brothers were assasinated, establishing himself as a foremost advocate for health care and civil rights. On the flipside, his image was seriously tarnished by the Chappaquiddick incident, in which a young woman named Mary Jo Kopechne was found drowned in his car; pundits point to the incident as the reason Kennedy was never a serious presidential candidate.

His death comes just two weeks after his sister, Special Olympics founder Eunice Kennedy Shriver, died at 88.

Kennedy is survived by his wife, Vicki and his children, Ted Jr., Patrick and Kara. Funeral plans are pending.