Jim Jeffords won a seat in the Vermont State Senate in 1966. He followed that success in 1968 with a victory in the race for attorney general of Vermont. He was a Presidential Elector for Vermont in 1972, and voted for reelection of the Nixon-Agnew ticket. Jeffords sought the Republican Party nomination for Governor in 1972, but was defeated in the primary by Luther “Fred” Hackett. In 1974, after winning the Republican nomination with a plurality in a three-way race, he won Vermont’s sole seat in the U.S. House of Representatives, where he served for 14 years and was the ranking Republican member of the House Education and Labor Committee. In 1988, Jeffords was elected to the U.S. Senate, and was reelected in 1994 and 2000. Jim Jeffords’ work in Congress focused on legislation involving education, job training and individuals with disabilities. In his later years in the Senate, his emphasis shifted somewhat, as he pushed through Congress several important pieces of environmental legislations. He was, together with Paul Simon, credited by Canadian Lieutenant-General Roméo Dallaire, Force Commander of the United Nations Assistance Mission for Rwanda (UNAMIR) from 1993 to 1994, for actively lobbying the US administration into mounting a humanitarian mission to Rwanda during the Rwandan Genocide. According to Dallaire’s book, Shake Hands with the Devil, he “owe(s) a great debt of gratitude” to both senators. Jim Jeffords was one of the founders of the Congressional Solar Coalition and the Congressional Arts Caucus. Jeffords was frequently recognized for his performance as a legislator, receiving Parenting magazine’s “Legislator of the Year” award in 1999, and the Sierra Club’s highest commendation in 2002. During part of his tenure in the Senate, Jeffords sat at the Candy Desk.

In April 2005, Jim Jeffords announced his decision not to run for re-election in 2006. Jeffords said his wife’s cancer and his own growing health concerns caused him to decide it was time to retire. On September 27, 2006, Jeffords delivered his farewell speech on the Senate floor. Floor speeches by and in tribute to retiring senators are a Senate tradition, but only one Republican senator, Chuck Grassley of Iowa, spoke on the floor in praise of Jeffords. The 70-year-old incumbent decided to retire despite consensus within the political community that he had good opportunity to win re-election in 2006. Governor Jim Douglas opted not to run, and Richard Tarrant won the Republican nomination. Bernie Sanders, then the only independent in the U.S. House, ran as an independent. Sanders also won the Democratic nomination by write-in, but declined it. In the general election, Sanders defeated Tarrant and four minor candidates, receiving 65 percent of the vote. Jim Jeffords died of Alzheimer’s disease on August 18, 2014, at Knollwood, a military retirement facility in Washington, D.C., where he had lived for eight years. He was 80 years old. He was buried at Northam Cemetery in North Shrewsbury.