Sen. Thomas KennedySen. Thomas Kennedy, a Brockton Democrat and fixture at the Massachusetts State House for more than three decades, passed away on Sunday night, according to his family. He was 63.

Kennedy joined the House in 1983 and won election to the Senate in 2008 where he most recently served as co-chair of committees on Election Laws and Consumer Protection and Professional Licensure.

According to someone close to the family, he had been undergoing treatment for cancer and died of complications.

In a Facebook post overnight, Kennedy's sister Mary Kennedy Bardsley wrote: "Our hearts are broken...May you be raised up on eagle's wings, dear brother Tommy...oh how we loved you so...! Rest in peace."

Kennedy joined the House in 1983 after serving on the Brockton City Council. In 2008, he won the Second Plymouth and Bristol Senate seat.

The senator used a wheelchair after being paralyzed in an accident earlier in his life. He had been studying to become a priest in the Catholic Church before returning home to Brockton in 1973 after the accident and beginning a career in government as ombudsman for the City of Brockton.

In the Legislature, aides remembered him on Monday as having a passionate voice and prominent role in helping to preserve gay marriage in Massachusetts, and noted that he lived just long enough to see it become legalized across the country.

"On behalf of the members of the Senate, we are deeply saddened by the passing of Senator Tom Kennedy," Senate President Stanley Rosenberg said in a statement. "He was a great friend, colleague, and public servant. He devoted his life to serving the people of his community and was proud of his working class roots. His voice will be missed in the Senate. Our hearts and prayers go out to his friends and family."