Boston ? For nearly half a century, Sen. Edward Kennedy has guarded his family’s political legacy. Stricken with cancer and as Congress takes up his signature issue, he is tending to his own.

Kennedy asked Massachusetts lawmakers to change state law to give Gov. Deval Patrick, a fellow Democrat and supporter of President Barack Obama, the ability to appoint an interim replacement to Kennedy’s seat should Kennedy be unable to continue serving.

Under state law, an election is required within 145-160 days after a Senate seat becomes vacant. That would temporarily leave Massachusetts without a voice in the Senate — and Senate Democrats potentially one vote short on any health care overhaul legislation.

Kennedy said he supports the special election process, but wants to ensure the seat is filled during the course of the election.