The 90-year-old Proxmire, who suffered from Alzheimer's disease, died around 1 a.m. EST Thursday at Copper Ridge, a convalescent home in Sykesville, Md., Copper Ridge spokeswoman Mindy Brandt said. She said she could not provide any details about his death.
Well respected for his intelligence and hard work, Proxmire was also a thorn in the side of political leaders and lobbyists during his three decades in the Senate, reports CBS News correspondent Bob Fuss. He waged a tireless campaign against wasteful spending large and small, complaining of billion-dollar boondoggles and trying once to stop construction of a new Senate gym.
He is perhaps best known for his annual "Golden Fleece" awards, in which he singled out particularly wasteful use of the taxpayer's money.
"Senator Proxmire leaves behind an unparalleled legacy as a defender of the American taxpayer and one of the hardest working Senators in U.S. history," said Sen. Russ Feingold, D-Wis. "Whether he was handing out his Golden Fleece Awards to keep government waste in check or casting one of his more than 10,000 roll call votes, William Proxmire always had the people of Wisconsin at the forefront of his mind."
Proxmire, who also became a familiar face on the television network Sunday news shows, was elected to the Senate in 1957 in a special election to fill the seat left vacant by the death of Sen. Joseph McCarthy.
He was re-elected in 1958 to his first six-year term and was returned to the same post in 1964, 1970, 1976 and 1982.
Long before the McCain-Feingold campaign finance reform law was a twinkle in the eye of lawmakers, and at a time when millions were spent campaigning for Senate seats, Proxmire made a point of accepting no contributions. In 1982 he registered only $145.10 in campaign costs, yet gleaned 64 percent of the vote.
Over the years, the rebel Democrat developed an image of penny-pinching populism that played well with his homestate voters. But his support of the expensive system of dairy price supports — widely criticized by others as symbolic of government largess gone amok — won him strong backing from his state's dairy farmers.
The son of a wealthy physician in Lake Forest, Ill., Proxmire graduated from Yale University and Harvard Business School. He served with military intelligence in World War II and later moved to Wisconsin to begin a career in politics.
After three unsuccessful attempts at winning the governorship, Proxmire won McCarthy's vacant seat.
Soon he carved out an independent streak on Capitol Hill by introducing amendments without consulting the party heads, filibustering, and even criticizing the dictates of then-Majority Leader Lyndon B. Johnson.
In that respect, he resembled to a certain degree the style of a latter-day maverick and government spending critic, Arizona Republican Sen. John McCain.