ALBANY – The defeat yesterday of a plan to build a Jets stadium and potential Olympic venue on the West Side of Manhattan could trigger a scramble to find a new site for the project, possibly in Queens, in time to rescue the mayor’s dream of having New York named host city of the 2012 Olympics.

The stadium, which had become one of the most controversial political issues here in a generation and the object of tens of millions of dollars in expenditures for political advertisements and lobbyists, was rejected as the two legislative leaders who have been holding up the project simply abstained from casting a vote on whether to provide state funds.

The decision by the majority leader of the Senate, Joseph Bruno, and the speaker of the Assembly, Sheldon Silver, to withhold their votes on a $300 million state subsidy followed a day of uncommon political theater in which Mr. Silver disclosed that he never intended to approve the $2.2 billion stadium and hordes of hostile union workers declared the Manhattan Democrat an enemy of organized labor.

The day belonged to Mr. Silver, who spent much of Sunday in apparent negotiations over the project with Mayor Bloomberg but who made clear early in the day that nothing could have won his approval for a project that he said he views as nothing more than a larger scheme to relocate New York’s financial center from Lower Manhattan to the West Side.

Mr. Bloomberg and Governor Pataki fervently supported the plan for what they called the New York Sports and Convention Center. Yesterday, however, when Mr. Silver was asked if the West Side stadium is now dead, he said: “It’s never been alive.”

If Mr. Silver’s earlier comments on the stadium suggested skeptical consideration, his comments yesterday suggested resolute defiance. Indeed, Mr. Silver’s earlier reservations appeared mere shadows of the concerns that he outlined in an impassioned prepared speech just before the repeatedly postponed vote by the Public Authorities Control Board. On that board, unanimity in the votes controlled by Messrs. Pataki, Silver, and Bruno was needed for the state financing, and thus the whole stadium plan, to move ahead.

In the speech, Mr. Silver equated opposition to the stadium with solidarity for the victims of the attacks of September 11, 2001. He called plans to develop the West Side instead of Lower Manhattan a type of betrayal. And he said he could not vote in favor of the project as a matter of conscience. He cast the issue as moral rather than political.

“This is not about the Olympics,” Mr. Silver said. “For me, this fight is about restoring New York City’s soul. It’s about honoring the sacrifices made on September 11. It’s about a moral obligation each and every one of us committed to when we saw those towers come down.”

Mr. Silver’s latest comments on Lower Manhattan development were his most pointed, and they suggest that the recent criticisms he has made that Messrs. Bloomberg and Pataki have pushed the West Side stadium at the expense of ground zero will only intensify. The two Republicans made a highly publicized offer of $820 million in subsidies for the area in late May. If Mr. Silver is willing to reject the stadium even after such a package for his district, he is unlikely to be quiet now that the project is dead.

Those incentives included $300 million for the World Trade Center memorial, $220 million for waterfront parks, $20 million for a new school, $32 million for traffic improvements, and $90 million for other cultural projects.

Though Messrs. Silver and Bruno shared responsibility for blocking the Jets stadium, their tactics in doing so diverged slightly at the end. The two men had seemed to be sharing notes up until early yesterday afternoon, when Mr. Bruno – who, like Messrs. Bloomberg and Pataki, is a Republican – called a press conference in which he chose to express his support for the Olympics rather than stress his opposition to the Jets stadium.

The tactic manifested itself at the raucous meeting of the control board later that afternoon, when Mr. Bruno’s representative, Mary Louise Mallick, proposed an amendment to a resolution that would guarantee state funds on the condition that New York is chosen as host of the 2012 games. When the resolution was not seconded by the representatives of either Messrs. Pataki or Silver, it died.

That the meeting took place at all was, to many, something of a surprise. Messrs. Bloomberg and Pataki have been trying to force a vote for months, saying the stadium must be approved before the July 6 meeting in Singapore at which the International Olympic Committee will vote on a host city for the games. The mayor and the governor argued that failure to secure a stadium would kill the city’s chances, a point that seemed to find confirmation in a preliminary report on host-city applicants issued by the IOC evaluation commission yesterday morning.

Messrs. Bruno and Silver had postponed two previous special meetings scheduled by the governor for a variety of reasons, calling the governor’s deadlines artificial and saying they lacked answers on a number of finance-related and legal questions. They lost one of those reasons Thursday, when a state Supreme Court judge, Justice Herman Cahn, ruled that the board of the Metropolitan Transportation Authority had not violated the law in March when it accepted the Jets’ $250 million bid to develop the stadium over the Hudson Rail Yards, rather than a richer bid submitted by the owners of Madison Square Garden.

Anticipating yesterday’s vote, Mr. Bloomberg arranged to meet Sunday with Mr. Silver for what many suspected were negotiations. Yet the theory that Mr. Silver was looking to gain a package of incentives for Lower Manhattan in exchange for his vote evaporated late Sunday when Mr. Silver emerged from Mr. Bloomberg’s office saying no progress had been made.

“I don’t know that there’s been any progress except for the fact that we are talking,” Mr. Silver said.

The consensus yesterday among aides to Mr. Pataki was that Mr. Bloomberg had underestimated the Assembly speaker’s abilities as a negotiator. One aide said Mr. Pataki had warned Mr. Bloomberg about Mr. Silver’s tactics, to no avail.

“After the original meeting was postponed, it looked like Shelley and Joe were on the run,” the aide said, referring to the legislative leaders. “We said make them vote against the stadium, and the mayor said we could sweet-talk them.

“I think at this point the mayor just wants this behind him,” the aide continued. “He loses.”

The actual vote of the control board took place in a pressure-cooker atmosphere, with roughly 200 union workers shouting in a humid conference room for more than two hours, as aides to the three voting members hashed out their plan. When one of the nonvoting members of the board, Senator Thomas Duane, Democrat of Manhattan, entered the room, he was circled on three sides and shouted down by an angry horde.

Mr. Duane, a vocal opponent of the project, later sought to delay the meeting by raising a series of concerns to the board’s chairman, John Cape, who represented Mr. Pataki at the meeting. Mr. Duane’s questions, aimed at establishing more reasons to oppose the project, drew loud shouts from the union laborers, who pressed in on the small table at which the voting members sat. After Mr. Duane was directed by Mr. Cape to refrain from asking additional questions, a motion was made to vote on the stadium proposal.

When the representatives of Messrs. Silver and Bruno refrained from voting, confusion ensued. Mr. Cape said he thought Ms. Mallick’s amendment counted as a second to his resolution on the stadium vote. When she explained that the proposal was conditioned on an affirmative vote on the stadium, Mr. Cape called a two-minute recess to review parliamentary procedure.

After all parties agreed that no second had been made to Mr. Cape’s original stadium resolution, Ms. Mallick and the representative for Mr. Silver, Steven Pleydle, chose to abstain from a vote. At that, Mr. Cape declared the issue dead.

“Pursuant to the statute that establishes the Public Authorities Control Board, all affirmative votes of the board must be unanimous. Since there are not three affirmative votes, I deem that the approval was not unanimous and therefore that the project resolution has been defeated.”

As Mr. Cape and the other board members hurried out of the room through a back door, the crowed erupted into a chant: “Silver’s got to go. Silver’s got to go. Silver’s got to go.”

With the West Side project defeated, attention now turns to alternative sites for a potential Olympic stadium. The Jets have so far refused to consider a stadium outside Manhattan, a stance team officials repeated yesterday.

Mr. Silver indicated he would support an Olympic facility at Willets Point, Queens, which would be near Shea Stadium and the U.S. National Tennis Center, but Mr. Bloomberg’s enthusiasm for the Summer Games could wane, an aide to the mayor said. The aide, speaking on condition of anonymity, said Mr. Bloomberg is now unlikely to press for the games at the Singapore meeting in four weeks.

The Jets, meanwhile, expressed outrage at yesterday’s rejection. They blamed Cablevision, owners of Madison Square Garden, for defeating the project, and vowed to continue their fight for a stadium in Manhattan. Team officials hope to move from the Meadowlands in New Jersey for the 2009 season and to have the 2010 Super Bowl played in their Manhattan home.

“Today is a setback,” the president of the team, Jay Cross, said in a statement. “But it is not the final chapter to be written in our quest to build a home for the New York Jets in Manhattan. Four years of hard work and planning will not be washed away in a single day.”

It also was unclear yesterday what might become of the rail yards over which the Jets stadium was to be built.

A major redevelopment project planned for the area could go forward without the Jets stadium as a centerpiece. The City Council has already approved rezoning for much of the area that would be redeveloped, but a new bidding process would have to take place for the 13-acre parcel, where the Jets hoped to build a 75,000-seat stadium on a platform financed by the city and with a retractable roof financed by the state.