Sen. Jim Jeffords died Monday morning at the Knollwood Military Retirement Residence in Washington, D.C.
He was 80 years old. Jeffords had lived at Knollwood since his wife died of ovarian cancer eight years ago.
The Vermont congressman and senator served 32 years in Congress until he retired in 2006 after he was diagnosed with Alzheimer's disease.
Jeffords became famous in May 2001 when he left the Republican Party to become an independent and began caucusing with the Democrats in the Senate.
It was a historic turning point for the 50-50 Senate. His switch instantly turned the Republican Senate over to the Democrats, and suddenly, President George W. Bush, who had openly spurned Jeffords, no longer had control of the Senate.
Jeffords had been at odds with the party since he took office as a congressman in 1975, and he told the Associated Press at the time: "It's been mounting over 20 years."
Jeffords was elected to Congress in 1974 and represented Vermont in Washington, D.C., as a member of the U.S. House of Representatives and then as a senator.
Sen. Patrick Leahy, D-Vt., who served in Congress with Jeffords for 30 years, counted the senator as a friend. "He was a Vermonter through and through, drawn to political life to make a difference for our state and nation," Leahy said in a statement. "Part of his legacy will also stand as an enduring chapter of the Senate's history."
Gov. Peter Shumlin remembered Jeffords as a "true gentleman and an independent-minded maverick in the best tradition of our state.
"Jim followed in the footsteps of Sens. Bob Stafford and George Aiken, always putting the interests of Vermonters and the nation ahead of partisan politics. He followed his sense of right in all that he did, and was never afraid to seek compromise by reaching across the aisle for the good of our country," Shumlin said in a statement.