WINCHELL: GOSSIP, POWER AND THE CULTURE OF CELEBRITY. By Neal Gabler. Alfred A. Knopf. $30. 681 pp.

Although he would die a defeated and largely reviled man, Walter Winchell presided over American mass culture for several decades, a self-appointed arbiter of power and taste, and an eerie harbinger of the culture of celebrity and gossip that would take hold in the country in the years to come.

In Neal Gabler’s enthralling new biography, Winchell emerges as a strangely emblematic figure – an avatar of “a cultural revolution in which control of the American agenda shifted from the mandarins of high culture to the new masters of mass culture.”

In the 1920s, Gabler observes, Winchell’s gossip column – with its irreverent debunking of the rich and famous – spoke to a society seething with new egalitarian impulses and discontents.

During the Depression, his hectic descriptions of Broadway openings and Hollywood shenanigans provided a glamorous escape from the cruel realities of the Depression, while his New Deal populism buttressed his pose as a champion of the people.

And in the years before and during World War II, his impassioned denunciations of Hitler and his calls to arms galvanized and echoed the nation’s commitment to war.

In the course of his career, Gabler argues, Winchell helped redefine the media’s role in American society, introducing concepts all too familiar today: journalism as entertainment, celebrity gossip as news, opinion-making as reportage.

As a leader in “the tabloid revolution,” Gabler adds, Winchell not only provided his readers with sensationalistic stories, but also “purveyed a cosmology, an attitude toward the world which was every bit as rich as the cosmology of the traditional press.”

Writing that Winchell was “arguably one of the principal architects” of modern American culture, Gabler turns the columnist’s life into the springboard for a fascinating social history. At the same time, he uses a novelistic approach to give the reader a vivid, psychologically acute portrait of Winchell himself.

Winchell’s sensibility, Gabler tells us, was indelibly shaped by his impoverished childhood in Harlem and by his early, scrambling years as a performer in vaudeville. The latter would endow him with a compulsive desire to entertain and a nihilistic sense of the precariousness of attachments.

After the war and Roosevelt’s death, Winchell’s liberalism began to sour. Truman disappointed him and so did Dewey and Henry Wallace. By the early ’50s, he had become an ardent supporter of Joseph McCarthy.

By then, Gabler observes, Winchell’s columns and broadcasts had grown increasingly vituperative and vindictive. All pretense of populist sentiment had vanished, as he used his power to settle purely personal scores and reward a dwindling number of friends.

In fact, Winchell’s private life had grown empty and acrimonious as well. He rarely saw his wife, June. His son, Walt, committed suicide.

And Winchell broke up his daughter Walda’s romance with a producer named Billy Cahn by questioning her sanity and defaming Cahn’s reputation, acts that would help sully Winchell’s own reputation, when they were incorporated into the portrait of a vindictive gossip columnist in the 1957 movie The Sweet Smell of Success.

Having celebrated the cult of the ephemeral celebrity, he died in 1972 by the very unforgiving rules of fame he had helped to invent, alone and forgotten.