The nation's chief Olympics official emphasized that New York City will lose any chance of holding the 2012 Summer Games if the proposed stadium isn't approved before the host city is selected - and Assembly Speaker Sheldon Silver and Senate Majority Leader Joe Bruno would be to blame.

"The [International Olympic Committee] has made it clear that without full approval of the proposed Olympic stadium before the IOC vote, New York's bid will not be successful," U.S. Olympic Committee Chairman Peter Ueberroth wrote in a May5 letter to Silver and Bruno.

In the letter, obtained by the Daily News, Ueberroth warned "the IOC will simply not take the risk of awarding the Games to a city that has not secured the necessary approvals for this marquee Olympic venue."

Failure to approve the proposed stadium, Ueberroth continued, "would grievously damage New York's Olympic bid and America's Olympic movement."

Ueberroth, the former Major League Baseball commissioner, knows something about luring the Olympics; he was chief executive of the 1984 Summer Games in Los Angeles.

Five cities - New York, Paris, London, Moscow and Madrid - are competing for the 2012 Games. The IOC will select the host city in Singapore on July 6.

The proposed $1.9 billion stadium needs the approval of the Public Authorities Control Board, a state panel controlled by Silver (D-Manhattan), Bruno (R-Rensselaer) and Gov. Pataki.

Pataki supports the project, while Silver and Bruno are officially neutral, although both have repeatedly voiced criticism.

The panel had been scheduled to vote on the stadium on Wednesday, but Bruno requested a postponement. Pataki rescheduled the vote for next week, but Silver could seek another delay.

A source told The News that Ueberroth sent the letter in part because Silver and Bruno publicly expressed doubt about the need to get the stadium approved before July 6.

Silver and Bruno vehemently dismissed accusations yesterday that the lawmakers are endangering the city's bid.

"The IOC doesn't care if the stadium is in Queens, Manhattan, the Bronx, Brooklyn or Staten Island," Silver told The News.

"I support the Olympics coming to New York City and would work to ensure all necessary venues and facilities for a fully successful Olympics are in place by 2012 if the city wins the bid."

Bruno spokesman John McArdle called allegations "nonsense." The senator is committed to building "whatever we need" if New York wins the Games, McArdle said.

Yet the logjam in Albany is clearly angering NYC2012, the city's bid committee, whose leaders welcomed Ueberroth's letter.

"To ignore the forceful statements of America's most respected Olympic leader only shows that the delays are pure politics," a senior NYC2012 official told The News on condition of anonymity.