The Pataki administration is moving to terminate its agreements with two of the city’s most powerful developers, Vornado Realty Trust and the Related Companies, to build Moynihan Station after the governor’s $900 million plan was rejected yesterday in Albany by a representative of Speaker Sheldon Silver.

Governor Pataki had hoped to break ground on Moynihan Station before he leaves office at the end of the year, but yesterday’s rejection, represents a major setback for the project and threatens to delay any reincarnations of the plan under a new gubernatorial administration.

“Speaker Silver has single-handily prevented the most important civic and transportation project in the nation today from proceeding,” Mr. Pataki said in a statement yesterday.

The assemblyman who represents the district that includes the proposed project, Richard Gottfried, a Democrat, blamed the governor for failing to reach a compromise.

“Governor Pataki has picked up his ball and gone home, because the Assembly didn’t want to play the game his way. His action today was pretty petty,” Mr. Gottfried said.

It was the second major public project on Manhattan’s West Side rejected by Mr. Silver in the last 16 months. In June 2005, he killed the Bloomberg administration’s vision of a building an Olympic stadium to be used by the Jets on top of the Hudson rail yards.

Unlike the city’s West Side stadium plan, the state’s Moynihan Station project enjoyed near unanimous support from civic organizations and elected officials. In more than eight years of planning, a host of officials, including Presidents Clinton and Bush, Mayors Giuliani and Bloomberg, and even the Dalai Lama, on a visit to New York, threw their support behind the vision of the late Senator Moynihan to transform the landmarked Farley Post Office building, with its monumental Corinthian colonnade, into a transit hub and another grand entrance to New York.

While Mr. Pataki blamed Mr. Silver for blocking his plan, critics of the governor say the proposal collapsed under the weight of the more ambitious project proposed byVornado and Related.

In May, the developers circulated preliminary plans to selected civic groups and public officials for a grander public and private project, earning rave reviews. In addition to creating Moynihan Station, the developers would rebuild Madison Square Garden at the west side of the Farley building, conduct a major renovation of the existing Penn Station, open it to daylight, and expand its capacity. They would also develop two or three towers on today’s Garden site.

The developers have said the plan, called Plan B, would require a tall stack of approvals, take more than seven years to complete, would earn them more than $1 billion. State officials say the plan would require public subsidies of between $1 billion and $2 billion.

The Pataki administration, in pursuing final approval of their more modest plan, decided on a strategy to get a shovel in the ground on Moynihan Station, and left a vague option in its project plan to allow for a Madison Square Garden move into the west side of the Farley building at a later date. They said the plan rejected yesterday was a prerequisite for the larger plan, and would in no way interfere with Plan B.

Mr. Silver has said in various ways since the governor’s plan first came before him August that he preferred the developers’ grander vision.

The president of the Partnership for New York City, Kathryn Wylde, said that while she supports Moynihan Station, it is “not close” to what would be achieved with Plan B, the creation of a transit hub that would rival Grand Central Station. She said she questioned why the Pataki administration did not acknowledge the larger goal in their pursuit of the smaller project.

“Apparently they didn’t feel there was time to do the entire plan, even though everyone universally acknowledges that this is what we should be doing,” Ms. Wylde said.

State officials have said the rejection of the plan by Albany Democrats in politics at its worst. They say that Mr. Silver was swayed by the owners of Madison Square Garden, the Dolan family, who employ lobbyist Patricia Lynch, Mr. Silver’s former chief of staff. The Dolans, they say, think that if Plan B is combined with Moynihan Station it will have a better chance of being approved and moving forward.

Mr. Pataki said yesterday, “New Yorkers and visitors from around the world should not be held hostage to an effort to finance a new Madison Square Garden on the backs of taxpayers.”

Other development analysts say that the Moynihan project was weakened by an approaching change in the governor’s office and that the front-runner to take over as governor in January, Eliot Spitzer, could be tiring of the flurry of ribbon cuttings in the sunset of Mr. Pataki’s term.