He was the front-runner for the Democratic nomination in 1972 until he destroyed his own chances by losing his temper during the New Hampshire primary. The leading local newspaper, the Manchester Union-Leader, owned by the extreme right-wing publisher William Loeb, had not only attacked him; it had insulted his wife.
Muskie was so angry that he drove down to the Union-Leader, followed by several television crews. Perched on a flatbed truck with the news- paper's offices as a backdrop, Muskie denounced Loeb so emotionally that it looked as if he burst into tears. (Some said it was melting snowflakes.) He later admitted that going down to the newspaper's office was "a mistake, a whopper".
The episode is a classic instance of the power of television to convey a non-verbal message. "It changed people's minds about me," he later told the author Theodore H. White. "They were looking for a strong guy, and here I was weak."
That was not the only time when Muskie came close to the highest political peaks. In 1968, when he was the vice- presidential candidate on the Democratic ticket with Senator Hubert Humphrey, several polls suggested that, if Muskie had been the candidate, he would have won. As it was, it is often forgotten that Richard Nixon only won by a narrow margin, with the Humphrey-Muskie team gaining on him in the last hours before the polls closed.
In 1972 Muskie won the first Democratic primary in New Hampshire, and might well have won the Democratic presidential nomination had it not been for the Union-Leader incident and for a cynical "dirty tricks" campaign by the Nixon campaign.
The President's men circulated a wholly faked letter purporting to show that Muskie had used the word "Canucks", a contemptuous word for French- Canadians, who are an important part of the Democratic constituency in New Hampshire. The deception became known when the Nixon man, a certain Ken Clawson, was foolish enough to boast of his authorship of the "Canuck" letter to an attractive female reporter on the Washington Post.
In 1976 Muskie was in the final in the contest to be Jimmy Carter's Vice- President. Carter himself confided to his diary that it was a close thing between Muskie and Walter F. "Fritz" Mondale, who eventually became Vice-President.
Muskie, who had been Governor of Maine from 1955 to 1959 and then a United States Senator from 1959 until 1980, was rewarded by President Carter in that year by appointment as his Secretary of State, a job Muskie greatly enjoyed and did very creditably, though he once confided that it was one job "that never crossed my mind".
Muskie's role was not to get involved in the detail of negotiations, for example, over the return of the American hostages in Tehran. That, and much else of the detail, was left to the Deputy Secretary, Warren Christopher, now President Clinton's Secretary of State. But Carter wrote in his memoirs that "Ed brought to the Secretary's office a broad and mature understanding of our nation itself and its international role".
Muskie's parents were Polish immigrants, his father a tailor whose name was changed for him from Marciszewski by immigration officials. He was born in Rumford, a western Maine papermill town, in 1914. He worked his way through a small local college, Bates, and then graduated from Cornell Law School before setting up a law practice in Waterville, Maine.
During the Second World War he served in the US Navy in destroyer escorts. He returned to Waterville and was elected to the Maine legislature in 1946. From 1955 to 1959 he served as Governor of Maine, where he was a pioneer in pushing for laws to clear up air and water pollution. He was elected to the United States Senate in 1959.
Six foot four with a craggy, lugubrious face, Muskie was good company and liked a drink in private. He was a conscientious and honourable politician with a fine speaking voice who lacked only flair. But he did have a temper, and when roused could swear with naval vocabulary.
Early on in his career in the Senate, he showed that he was not a man to be cheaply bought. It was at a time when Senator Lyndon B. Johnson, then the Senate majority leader, was playing a delicate game with his conservative Southern Democratic colleagues over Rule 22, which allowed Southern Senators to filibuster a civil rights bill.
Johnson made it plain to Muskie and other freshman senators that, if they went along with a conservative version of an amendment to Rule 22, one that would effectively enable the South to postpone civil rights legislation in favour of black citizens, they would be rewarded with assignment to desirable committee assignments. Muskie refused and was punished by two comparatively insignificant committee assignments, to the Government Operations and Public Works committees.
His long career in the Senate was characterised by solid work rather than by glamorous speechifying or the sponsorship of famous legislation. His somewhat dour approach to politics was well illustrated by his remark when asked for a comment on Nixon's victory in 1968. "In Maine," he replied, "we have a saying that you don't say anything that doesn't improve on silence."
Shortly after that 1968 defeat, Muskie quietly convassed his colleagues to see if there was support for his becoming a Democratic Whip, a job that would have led to his becoming the Senate majority leader in succession to Senator Mike Mansfield in due course. Twenty-nine voters would have been enough to get him the job. It was typical of Muskie that when he found he had only 24 immediate supporters, instead of trying to win more of his colleagues over by a public bid for the job, he quietly accepted defeat.
After Jimmy Carter was defeated by Ronald Reagan in 1980, Muskie joined a Washington law firm, Chadbourne & Parke, where he remained a partner until his death. He divided his time between Washington DC and a holiday home at Kennebunk, near President Bush's home. He was one of the co-authors of the Tower report commissioned by President Reagan into the Iran-Contra scandal in the 1980s.
Muskie married Jane Gray of Waterville in 1948. They had two sons and three daughters. His concern for the environment came from his love of the outdoors. He loved to fish in Maine rivers, hunt in Maine's vast forests and even to swim in its icy sea.
Edmund Sixtus Muskie, lawyer and politician: born Rumford, Maine 28 March 1914; member, Maine House of Representatives 1947-51; Democratic Floor leader 1949-51; District Director for Maine, Office of Price Stabilisation 1951-52; City Solicitor, Waterville, Maine 1954-55; Governor of the State of Maine 1955-59; US Senator from Maine 1959-80; Senate Assistant Majority Whip 1966-80; Chair, Senate Budget Committee 1974-80; Secretary of State 1980-81; senior partner, Chadbourne & Parke 1981-96; author of Journeys 1972; married 1948 Jane Gray (two sons, three daughters); died Washington DC 26 March 1996.