Jack Newfield, who died Monday night at age 66, was one of the greatest muckraking newspapermen of his generation, a passionate assailant of corruption, inequity, and violence of all kinds – except boxing, which he adored.

“When we speak of America’s great crusading journalists, Jack Newfield will be remembered among them,” Mayor Bloomberg said yesterday. “He will be remembered as a writer who, guided by his conscience, shaped his times.”

“He was a terrific fighter for causes, with his typewriter and his brilliant mind, and he was a lover, loved Bobby Kennedy and newspapers,” Governor Cuomo, a friend of Newfield’s since the early 1960s, said. “He hated Vietnam and the death penalty and things that were unjust. He must have hated leaving at 66.”

Newfield, who worked for many New York newspapers over the years and most recently for The New York Sun, had a clear idea of how he fit into the political spectrum. According to a story Newfield told friends, the editor of the Sun, Seth Lipsky, once referred to the columnist as “liberal.” Newfield responded hotly that he was no liberal, but rather a radical.

Jack Newfield had referred to himself as a radical since the 1960s, but he balanced his passions with the objectivity of a seasoned journalist. The writer and the activist were one: In his recent memoir, “Somebody’s Gotta Tell It,” he wrote of the tumultuous 1968 Democratic National Convention in Chicago: “I threw a typewriter out the window of the Hilton Hotel, at the police, when I saw kids getting beaten.”

Newfield went to work at the Village Voice in the early 1960s, and from then on was almost continuously in print for a New York audience. He later took jobs at the Daily News, the New York Observer, the Post, and most recently was a columnist for the Sun, where he broke a number of stories about corruption within the Brooklyn courts and Democratic Party.

Newfield also wrote 10 books, which well chart the arc of his career. The first were “A Prophetic Minority,” an early, frontline view of the rise of what became called the New Left, and “Robert Kennedy: a Memoir,” written in the aftermath of the presidential candidate’s assassination in June 1968.

Bobby Kennedy was Newfield’s most important love, a mainstream politician with whom the radical became smitten. It was a transformative love that grew during the 81 days Newfield, who was then 28, spent with Kennedy on the campaign trail that year. Newfield credited Kennedy with inspiring him to push for social justice. Thanks to Kennedy, Newfield found a taste for “conniving with the mainstream,” in the words of Victor Navasky, publisher of the Nation.

“City For Sale” (1988), written with Wayne Barrett, was a sweeping expose of corruption in the administration of Mayor Koch and acted as an apt punctuation mark to Newfield’s 24 years of muckraking at the Village Voice.

In 1995, Newfield published “Only in America,” in which he used a lifetime of both boxing knowledge and reporting skills to indict both the promoter Don King and the shabby state of the sport in general. He also won an Emmy for the PBS documentary “Don King: Unauthorized.”

In 2002, still going strong, Newfield published his memoir.

Jack Newfield was born at Brooklyn into a secular Jewish family. He never really knew his father, who collapsed and died on a subway when the son was just 4. While his mother struggled to put food on the table of their Bedford-Stuyvesant home, Newfield attended Boys High School, where he edited the student newspaper. A Dodgers fan, he grew up idolizing Jackie Robinson, while a friend later described Newfield as “blacker than the blacks” in his choice of music. “Only when I got to Hunter College, which was 95 percent white, did I realize how unorthodox and underground my taste was,” Newfield wrote.

He began his career as an activist under the influence of Michael Harrington, author of “The Other America,” and went south to participate to participate in civil-rights demonstrations.

Newfield also developed a taste for the best writers among the New York newspaper columnists: Jimmy Cannon and Murray Kempton.

After knocking around at various New York publications – he was fired at the West Side News, Women’s Wear Daily, and the Daily Mirror, the last for deliberately destroying wire copy about the Bay of Pigs – Newfield was finally hired in 1964 to work at the Voice, which was then much less prominent an institution than it is today.

The weekly’s founder and editor, Dan Wolf, told Newfield: “You have the gift of distorting things in the direction of emotional truth. Therefore, you have a special need to appreciate complexity, triple check every fact, and never forget you might be wrong.” Wolf would be Newfield’s mentor for many years until the relationship collapsed amid recriminations.

Newfield thrived at the Voice, covering countercultural political ferment, boxing, folk music, and anything else that interested him. He began contributing pieces on politics to the Nation and in 1966 published “A Prophetic Minority.”

Newfield’s involvement in leftist politics grew, and in 1968 he joined the Kennedy campaign, an act he labeled “crossing the line” between journalism and politics. Kennedy’s and Martin Luther King Jr.’s assassinations, the debacle of the Chicago convention, and the subsequent fragmentation of the left seemed to concentrate Newfield’s mind. Once he could write, he was “propot, pro-riot, and pro-Cong.” In one of his last articles for the Sun, Newfield wrote, “What we called The Movement went nuts from frustration by 1968.The Black Panthers and the Weathermen began to glorify violence. Anti-Americanism became a kind of mass madness. Leaders of The Movement became agnostic about democracy, or downright hostile to it. And then two clowns tried to lead a revolution, Jerry Rubin and Abbie Hoffman. So The Movement became a clown show.”

Newfield began muckraking for the Voice with renewed vigor. He wrote of a Staten Island congressman: “almost every variety of vice, almost every sample of sleaze, that might serve to illustrate the axiom that ‘power corrupts’ can be glimpsed in John Murphy’s 17 years in Congress.” Murphy subsequently earned a federal sentence when he was caught up in the Abscam bribery scandal.

Newfield crusaded for victims of lead paint and against corruption in the nursing-home industry. In 1972, he initiated his annual “10 Worst Judges” list, and later his “10 Worst Landlords.”

Occasionally his items could seem scattershot, and on one occasion he lied that he had once heard Bella Abzug oppose the sale of jets to Israel “so that she might defeat Barry Farber.” He later publicly apologized.

During the 1980s, Newfield, along with two Voice reporters, Mr. Barrett and Joe Conason, led a series of investigations uncovering corruption in the Koch administration, which culminated in a number of convictions of Democratic Party bosses and the suicide of Donald Manes, the Queens borough president.

In 1988, Newfield moved to the Daily News as an investigative reporter and columnist. After just 15 months, which he described as “one of the most joyful periods of my career,” Newfield quit in solidarity when the newspaper’s unions struck.

Newfield was soon hired in a similar role by the New York Post, where he worked during the staff “mutiny” of 1992, when the paper teetered on the brink of financial collapse while shuttling between sketchy owners. Briefly the boss was Abe Hirschfeld, the parking-garage tycoon, developer, and frequent political candidate, who had been on one of Newfield’s worst-landlords lists and later went to prison after a murder-conspiracy conviction. When Hirschfeld took ownership, the staff put out a paper assailing him. Newfield’s column was headlined: “Who Is This Nut? Honest Abe Doesn’t Know Spit About Journalism.”

The bizarre episode ended with Rupert Murdoch’s taking ownership. Newfield stayed on at the Post until 2001, when he was fired as part of an editorial overhaul.

In recent years, Newfield wrote his memoirs, edited books about “American Monsters,” produced documentaries, and wrote for a number of publications. In post-September 11 New York, he was eager to expose what he saw as the unwarranted near-deification of Mayor Giuliani, and to track the progress of commitments the federal government made to the city in the aftermath of the terrorist attacks.

“As politics seemed more empty, I followed my instincts and started to write more, and with a fan’s enthusiasm about the arts and popular culture,” he told readers. Newfield wrote that he even began to be interested in his long-neglected Jewish roots, especially in the concept of tikkun olam – “repairing the world.”

Mr. Cuomo said he had discussed tikkun olam with Newfield and thought that the columnist’s crusading journalism came from the same impetus. The former governor said: “I told him, ‘You’re a hell of a Hebrew.’ “

“Jack Newfield was an inspiring newspaperman, and all of us at The New York Sun were thrilled when he threw in with us at the launch of this paper,” the Sun’s editor, Mr. Lipsky, said yesterday. “It turns out that he was not only a great columnist but also a wonderful colleague, mentor, and role model for a new generation of journalists starting out here at the Sun. You could see it when he entered the newsroom, as reporters and editors gathered round him or sidled up for a conversation. He became a friend of many of us here, and we will miss him.”

Jack Newfield

Born February 18, 1938, in Brooklyn; died December 20 at Columbia-Presbyterian Medical Center of metastatic kidney cancer; survived by his wife, Janie Eisenberg, and his children, Rebecca and Joseph.