At a small bar in Lower Manhattan, Mark Green stepped to the microphone before a few dozen supporters shortly after 10:30 p.m.

“As Deni has often remarked privately, and occasionally publicly, I am not a very good politician,” Mr. Green said, standing next to his wife, Deni Frand, and son and daughter. He proceeded to concede the race for the Democratic nomination for attorney general to Andrew Cuomo, a former federal housing secretary and the son of a three-term governor.

For Mr. Green, the stage was familiar.

The House of Representatives in 1980. The U.S. Senate in 1986. The Senate again in 1998. The mayor of New York in 2001. And now the state attorney general.

Sandwiched among the defeats in those races, Mark Green was twice elected as the city’s public advocate, but it may be Mr. Green’s five failed bids for higher office that serve as his political legacy. He’s raised more than $20 million for seven campaigns and accepted more than $5 million in public matching funds, but it’s never been enough.

With yesterday’s loss to Mr. Cuomo, the voters seem to have said a resounding “No” to Mr. Green.

After more than a quarter-century and seven campaigns, the end had finally come. “I will not seek office again,” Mr. Green told reporters after his concession speech. “I want to make my contribution as an advocate, as a writer, as a lawyer, and as a teacher, but I will not seek elective office again.

Mr. Green, 61, has written 21 books over a career in law and consumer advocacy that has spanned more than three decades. His performance as commissioner of the city’s Department of Consumer Affairs and later as the public advocate drew praise from the political establishment, but his message and, in particular, his hard-charging style, have never resonated with the electorate, observers said. “He gets defeated not because of his ideas, but because of his personality,” a political consultant, George Arzt, said.

The campaign for the Democratic attorney general nomination began as a race among former runner-ups, Messrs. Cuomo and Green, and political unknowns, Sean Patrick Maloney and Denise O’Donnell, but analysts say Mr. Cuomo used his statewide name recognition to lock up big party donors and pull away from the field.

While Mr. Green banked on support in the five boroughs, the Cuomo name was more widely known upstate and in Long Island, both from Mario Cuomo’s three terms as governor and Andrew’s unsuccessful bid for the statehouse in 2002.

More than the Cuomo name, however, political analysts say Mr. Green made a poor decision to run consistently negative campaigns — focusing too much on criticizing his opponents and not enough on trumpeting his own virtues. “Insiders feel that he did more damage to himself than he did to Andrew Cuomo,” Mr. Arzt said. “You have to give voters a reason to vote for you, and he never did that.”

Even after Mr. Green won the key endorsement of the New York Times, Mr. Cuomo’s lead widened in the polls.

Things could have turned out differently for Mr. Green. Many expected him to defeat then-political novice Michael Bloomberg for mayor in 2001, but the terrorist attacks of September 11 shifted the dynamic of the race, and a late endorsement by the hugely popular Mayor Giuliani threw the election to Mr. Bloomberg.

“If 9/11 didn’t happen, he might well have become the mayor of New York,” the president of Brooklyn, Marty Markowitz, a Green supporter, said.

Political observers said Mr. Green’s best bet was a senior-level appointment in a new administration in Albany, or perhaps even under Mr. Bloomberg.