Ted Kennedy, the “Liberal Lion,” and one of the longest serving senators in the U.S. history, died Tuesday evening at his home in Hyannisport, Mass., after a yearlong battle with brain cancer. He was 77.

His passing comes weeks after the death of his sister, Eunice Kennedy Shriver.

In a statement, the Kennedy family thanked “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.

“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. He loved this country and devoted his life to serving it. He always believed that our best days were still ahead, but it’s hard to imagine any of them without him.”

Kennedy, known as “Teddy,” was one of the most influential lawmakers in Washington. He was born into a political dynasty that was also stricken by numerous tragedies, including the assassinations of his brothers, President John F. Kennedy, and Sen. Robert Kennedy. His brother Joe was a pilot killed in World War II.

He was elected to the Senate in 1962, to the seat held by his brother, John.

Reuters reported that during Ted Kennedy’s nearly forty-plus years in the chamber he “became known as one of Washington’s most effective senators, crafting legislation by working with lawmakers and presidents of both parties, and finding unlikely allies.”

Last week, Sen. Kennedy had appealed to Massachusetts Gov. Deval L. Patrick to change the state law regarding Senate seat vacancies.

“Serving the people of Massachusetts in the United States Senate has been – and still is – the greatest honor of my pubic life. As I look ahead, I am convinced that enabling the Governor to fill a Senate vacancy though an interim appointment followed by a special election would best serve the people of our Commonwealth and country should a vacancy occur.

“I…urge you…to amend the law through the normal legislative process to provide for a temporary gubernatorial appointment until the special election occurs. To ensure a fair election process, I also urge that the Governor obtain, as a condition of appointment of the interim Senator, an explicit personal commitment not to become a candidate in the special election,” Kennedy’s letter said.

Earlier Tuesday, the Boston Globe reported that state Senate President Therese Murrary may consider giving Gov. Patrick the power to appoint a temporary successor to Kennedy.

“She is listening to the members and keeping an open mind,” state Sen. Robert O’Leary, a Democrat, told the newspaper. “I am full steam ahead and she understands that is fine with it.”

Kennedy was a staunch advocate for healthcare reform and civil rights. He published a column in Newsweek July 18 titled “The Cause of My Life: Inside the fight for universal health care,” where he made the case for quality, affordable care for all Americans.

Last year, I was diagnosed with a malignant brain tumor. Surgeons at Duke University Medical Center removed part of the tumor, and I had proton-beam radiation at Massachusetts General Hospital. I’ve undergone many rounds of chemotherapy and continue to receive treatment. Again, I have enjoyed the best medical care money (and a good insurance policy) can buy.

But quality care shouldn’t depend on your financial resources, or the type of job you have, or the medical condition you face. Every American should be able to get the same treatment that U.S. senators are entitled to.

This is the cause of my life. It is a key reason that I defied my illness last summer to speak at the Democratic convention in Denver—to support Barack Obama, but also to make sure, as I said, “that we will break the old gridlock and guarantee that every American…will have decent, quality health care as a fundamental right and not just a privilege.” For four decades I have carried this cause—from the floor of the United States Senate to every part of this country. It has never been merely a question of policy; it goes to the heart of my belief in a just society. Now the issue has more meaning for me—and more urgency—than ever before. But it’s always been deeply personal, because the importance of health care has been a recurrent lesson throughout most of my 77 years…

We will bring health-care reform to the Senate and House floors soon, and there will be a vote. A century-long struggle will reach its climax. We’re almost there…I believe the bill will pass, and we will end the disgrace of America as the only major industrialized nation in the world that doesn’t guarantee health care for all of its people.

In a statement, Speaker of the House Nancy Pelosi said, “Ted Kennedy’s dream of quality health care for all Americans will be made real this year because of his leadership and his inspiration.”