The Bloomberg administration announced an eleventh-hour deal last night to save the city’s Olympic bid. It scraps its original plan for Manhattan and would make a new Shea Stadium for the Mets in Flushing the central sporting venue for the 2012 Summer Games.

After more than two years of pushing his proposal to build a stadium by the Hudson River on the West Side and months of trying to convince the legislative leaders in Albany to get on board with his plan, Mayor Bloomberg said the modified blueprint to accommodate the 2012 Games would be presented to the International Olympic Committee today.

The plan calls for the New York Mets, whose home games are played in an aging baseball field they have outgrown, to build and pay for a new, 40,000-seat stadium on their parking lot just east of the existing facility.

The team would play at the site in the 2009, 2010, and 2011 baseball seasons and then leave for a year so that the city could build a sphere like addition around the stadium and reconfigure it as an 80,000-seat facility. That would be home to the opening ceremonies of the Games – if the city wins out next month over the other four finalists: Paris, London, Madrid, and Moscow.

In a striking move, the New York Yankees – the Subway Series rival to the Mets – have agreed to share their baseball field in the Bronx for the 2012 season if that becomes necessary.

“I think the analogy that we’re like the athlete who falls, and gets up, and dusts himself off, and pushes ahead is probably a good ways to describe New York,” Mr. Bloomberg said during a hastily called 7 p.m. news conference in the Blue Room at City Hall.

“We’ve spent the last week trying to find a ways to keep the dream alive,” he said. “We brainstormed, we collaborated, we pushed and we pulled, and all of us worked together trying to find some ways to make this happen, and I think over the last few days, we found it.”

Last Monday, the city’s Olympic bid was dealt what appeared to be a fatal blow when, after months of speculation, two of Albany’s most powerful lawmakers declined to approve the Jets’ proposal, backed by Mr. Bloomberg and Governor Pataki, for a $2.2 billion New York Sports and Convention Center over the Metropolitan Transportation Authority’s Hudson rail yards. That project would have received city and state subsidies valued at more than $1 billion.

Mr. Bloomberg and his deputy mayor for economic development, Daniel Doctoroff – a former investment banker who has spent more than a decade laying the groundwork for the city to win the Games – pitched the stadium as not just an Olympic venue, but also a home to the New York Jets football team and an expansion to the Jacob K. Javits Convention Center.

Mounting community opposition, resistance to the government subsidies, and concerns by the speaker of the state Assembly, Sheldon Silver, that the project would hurt the economy of Lower Manhattan ultimately thwarted Messrs. Bloomberg and Doctoroff.

Mets executives said last night that they did not know how much a new baseball stadium would cost and had no design in place. The plan calls for the city to pay $85 million and the state to pay $75 million for preparation of the site with special support pilings and for other necessary infrastructure.

The expenditures would require approval from the state Legislature and the City Council, but not until the 2007 fiscal year. That move could create a buffer for Mr. Bloomberg during an election year when one of his Democratic rivals, Gifford Miller, heads the City Council.

The plan would also require an additional $50 million each from the city and the state should New York be named the 2012 host city on July 6 in Singapore. Among other things, that money would go to building a new “warm-up and throwing field” where Shea Stadium now stands.

The chairman and chief operating officer of the Mets, Fred Wilpon, said he was humbled by the decision and would be thrilled to have his stadium as host for the Olympics.

After the news conference, he seemed less excited about the prospect of sharing a ballpark with the Yankees, but he staved off questions about how he and Yankees’ principal owner, George Steinbrenner, would handle that.

Yesterday – five days after he said the defeat of the Jets Olympic stadium had “let down America” – the mayor said Mr. Silver had agreed to the new plan, and City Hall quoted the Assembly speaker as saying he and the members of the Queens delegation “wholeheartedly support” the project. It would “not only keep alive New York City’s 2012 Olympic dream, but will also provide significant, long-term benefits to the entire metropolitan area,” the Manhattan Democrat was quoted as saying.

The mayor’s seemingly stubborn quest for the West Side stadium has, for the last several months, dogged him and amounted to a politically vulnerable Achilles heel. His Democratic challengers have for months been lobbying him to abandon his vision of an Olympic stadium in Manhattan in favor of a Queens venue, which they have argued would help redevelop an equally desolate part of the city.

Though Messrs. Bloomberg and Doctoroff told reporters they believe the International Olympic Committee would allow the late modification, as was signaled late last week, it was unclear exactly how the committee’s executive board would respond.

What is clear is that 72 hours leading up to the announcement City Hall was engaged in whirlwind negotiations with the Mets and the Yankees – who were generally unhappy tenants of Shea Stadium in the 1970s during the Bronx ballpark’s renovation.

Mr. Bloomberg, fresh from officiating the day before at the wedding of his daughter Emma at his sprawling Westchester home, seemed visibly ex cited by the teams’ cooperation.

“The Yankees and the Mets have put their rivalry aside to make sure that our bid can go forward,” Mr. Bloomberg said.

The mayor shrugged off the suggestion that it would be difficult to convince the International Olympic Committee of a plan that he had long been belittling.

“We went with what we thought was the best chance to get the Olympics. We couldn’t do it. I mean, what are you supposed to do – fall over and give up?” the mayor said. “That’s not what New York is all about.”

The mayor equated it to the four day timeline in which New York emerged as host city for the United Nations. Mr. Doctoroff said he thinks the deal was hammered out in record time – faster than the “96 hours it took to put the U.N. deal together” in 1946, when New York was selected.

Those on hand yesterday said the Willets Point area in Queens, which is now largely industrial, would be built into a thriving enclave and for the 2012 Games could be home to the main “press center” for the Olympics and its International Broadcast Center. The new facility, which would be the stadi um for track and field, the soccer finals, and the opening and closing ceremonies, would also be in an Olympic Park Cluster surrounded by sporting venues for several other events.

A deal with the Yankees, who are also planning a new stadium adjacent to their existing home, is also anticipated in the next week.

Mr. Miller, who had been planning legislation to block the mayor from financing the Jets’ stadium without approval from the City Council, issued a lukewarm statement last night.

“I hope the mayor’s announcement isn’t too little too late,” he said. “Had the mayor made the right choice of a Queens Olympic stadium much earlier, our bid wouldn’t be threatened by a cobbled-together, Eleventh-hour alternative.”

Another of the four Democratic mayoral hopefuls, Rep. Anthony Weiner of Queens, said the Willets Point stadium, for which he has been fighting since April 2004, was the right choice. Mr. Weiner, whose district also includes part of Brooklyn, said he would “stand with the mayor to make it happen.”