WASHINGTON (CNN) -- Sen. Ted Kennedy, who is battling brain cancer, is urging Massachusetts officials to change a law to allow for an immediate temporary replacement should a vacancy occur for one of his state's two Senate seats.
Under a 2004 Massachusetts law, a special election must be held 145 to 160 days after a Senate seat becomes vacant. The winner of that election would serve the remainder of a senator's unexpired term.
Kennedy, a Democrat who has represented Massachusetts in the Senate for nearly 47 years, was last re-elected in November 2006. His six-year term ends in January 2013.
In a letter to Gov. Deval Patrick and other state leaders, Kennedy said he supports the current law, "[b]ut I also believe it is vital for this Commonwealth to have two voices speaking for the needs of its citizens and two votes in the Senate during the approximately five months between a vacancy and an election."
Kennedy, 77, asks the governor and state leaders to "amend the law through the normal legislative process to provide for a temporary gubernatorial appointment until the special election occurs," according to the letter, dated July 2.
Democrats, who -- in collaboration with Independent Sen. Joe Lieberman of Connecticut -- control 60 votes in the 100-member Senate, face a tough battle this fall on President Barack Obama's health-care reform package. They have been trying to calculate votes without Kennedy, who has been unable to attend many sessions for months due to his illness.
Kennedy has championed universal health care for years and wants to make sure Democrats have the votes they may need for passage of a comprehensive bill.
He has called the issue "the cause of his life," and hopes to see legislation that will "guarantee that every American will have decent, quality health care as a fundamental right," as he said at the 2008 Democratic Convention.
"It's typical of Ted Kennedy to be thinking ahead, and about the people of Massachusetts, when the rest of us are thinking about him," Patrick, a Democrat, said in a statement.
Prior to 2004, Massachusetts law allowed the governor to appoint an immediate replacement in the event of a U.S. Senate vacancy. The heavily Democratic legislature changed the law, however, after Massachusetts Sen. John Kerry became the likely Democratic presidential nominee.
Critics charged the legislature with changing the statute to prevent then-Gov. Mitt Romney, a Republican, from picking a replacement for Kerry in the event of a Kerry victory over then-President George W. Bush.
Kennedy is currently the second-longest-serving member of the Senate, surpassed only by Democrat Robert Byrd of West Virginia. Calculations on Senate votes this fall also have included Byrd, who is 91.
-- CNN Senior Congressional Correspondent Dana Bash contributed to this report.