Cranston died at his home in Los Altos, his daughter-in-law Colette Cranston said. She said his son Kim found him slumped over a sink and paramedics were unable to revive him. The cause of death wasn't immediately known.
After Cranston's retirement from Congress, the Democrat largely dropped out of public view. But he continued to champion the cause of nuclear arms control, which had been the centerpiece of his political career and his 1984 campaign for president.
In 1996, he became chairman of the Gorbachev Foundation USA, a San Francisco-based think tank founded by former Soviet President Mikhail Gorbachev to promote world peace and nuclear disarmament.
"Sen. Cranston's life-long dedication to peace in the world and nuclear arms reduction have been inspirational to me," said Sen. Barbara Boxer, who took over Cranston's Senate seat in 1992. "My heart goes out to his family."
When Cranston announced in 1990 that he wouldn't seek a fifth Senate term, he cited only his diagnosis of prostate cancer. However, his approval rating at the time had plunged to a record low due to the savings and loan scandal and his relationship with Lincoln Savings & Loan President Charles Keating, who had just been indicted on securities fraud charges.
A Senate Ethics Committee investigation later led to a formal reprimand of Cranston and sanctions against four other senators, known as "the Keating Five," for intervening with federal regulators on Keating's behalf.
Cranston, who received nearly $1.2 million in political funds from Keating, initially insisted he had been "politically stupid" but ethically correct to intervene.
While he ultimately agreed to a finding that he had "engaged in an impermissible pattern of conduct in which fund raising and official activities were substantially linked in connection with Mr. Keating and Lincoln," he remained defiant.
In his final response to the reprimand on the Senate floor in 1991, Cranston declared that his actions "were not fundamentally different from the actions of many other senators."
The remark clouded the former majority whip and No. 2 Senate Democrat's relationship with his Senate colleagues, and Cranston's reputation as a champion of liberal activism and progressive reform never recovered from the scandal.
In a 1996 interview, Cranston said: "I don't feel any need for redemption."
"I'm satisfied with what I did in the Senate," he said. "I don't look back. I look forward."
In a 1985 speech, Cranston said he originally ran for the Senate "because there I can work on the issues of war and peace, and the environment, and justice, and opportunity."
It's "where I kept the commitment I made in my 1968 campaign and get us out of the tragic war in Vietna; where one act of mine helped keep us out of war in Angola ... one step I took, followed by many more, did much to prevent war in Angola, ... where I'm doing the utmost to dispel the threat of nuclear war that hangs over our children, darkening their days and filling their nights with fear," he said.
Cranston was a journalist before he became involved in politics. He was a lobbyist and then served two terms as California state controller before he was elected to the U.S. Senate on his second try in 1968. In 1977, he became assistant majority leader, or whip.
In 1983, at the age of 68, Cranston announced his candidacy for president, declaring that his age would be an advantage because, he said, the American people "want wisdom, maturity, proven capability" in the White House.
Cranston announced that ending the arms race would be the "paramount goal" of his campaign. But his campaign never attracted significant support, and he withdrew from the race for the Democratic nomination, later won by Walter Mondale.
Early in his Senate career, Cranston earned a reputation for uncanny skill in determining how senators would vote on an issue.
He "runs around with a pencil and a computer which is his mind and keeps a complete record on everyone's past voting record, future voting record, and apparently even their innermost thoughts," Sen. Dale McGee, D-Wyo., once said.
Cranston was born into a prosperous family in Palo Alto in 1914. After graduating from Stanford University in 1936, he started working for International News Service, reporting from London, Rome and Ethiopia.
He never lost his interest in journalism. In 1973, at the height of the Watergate scandal that drove President Nixon from office, Cranston introduced legislation to guarantee reporters the right to keep their informants confidential.
Cranston also edited the first unexpurgated English translation of Adolf Hitler's Mein Kampf published in the United States. Hitler successfully sued for copyright violation, and for decades, Cranston's resume proudly included the fact that he had been sued by the German dictator.
In 1939, Cranston became a lobbyist for the Common Council for American unity, an organization opposing discrimination against the foreign born. The same year, he and cartoonist Lee Falk wrote a play, "The Big Story," based on his newspaper experiences. It was tried out in New Jersey but never reached Broadway.
Cranston enlisted in the Army during World War II and was assigned to lecture on war aims. After the war, he wrote "The Killing of the Peace," a book about the Senate struggle over the League of Nations in the aftermath of World War I.
During the late 1940s, Cranston worked at his father's Palo Alto real estate firm and became president of United World Federalists, an organization advocating world government.
When he announced his presidential candidacy more than 30 years later, Canston said he no longer believed that world government was "a practical solution to problems in the form in which they now exist."
Cranston was married and divorced twice. His son Kim played key roles in his presidential campaign, including running a controversial vote registration program funded by Keating's contributions. Another son, Robin, was killed in a traffic accident at age 33 in 1980.
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