This is a new page from the well-read, well-studied congressional manual on financial prestidigitation.

In a year when every member's middle name is "Thrift," Congress has just rejected a chance to save $50 million or more on a new building for federal employes in New York.

Final Senate approval was given two weeks ago on a new $92 million structure in Jamaica, Queens. Last week, the proposal was zipping through House and Senate Appropriations subcommittees, even though the Office of Management and Budget says it is a wasteful venture.

The new building, to replace leased structures now housing Social Security Administration employes, will be one of six regional SSA processing centers around the country.

SSA and the government's property manager, the General Services Administration, insist the new building is essential for consolidating SSA components scattered elsewhere in the Queens area.

You might call that the fascade of the new building. But the foundation lies in earthy politics.This obscure building's complicated tale is a story about clout in Congress and how it counts when a legislator sees a chance to land a choice federal project for his district.

Here there were two legislators: Daniel Patrick Moynihan (D-N.Y.) in the House. They prevailed even though a well-known New York real estate company said it could provide the government with the office space it wanted to much less cost. And they prevailed easily; in Congress, spoilsports are rare on spoils questions.

In a House committee, after Rep. Barry M. Goldwater Jr. (R-Calif.) raised questions, he was outvoted handily -- 32 to 1. In a Senate committee, after Robert T. Stafford (R-Vt.) and Alan K. Simpson (R-Wyo.) raised questions, they, too, lost handily.

The story starts in 1978, when the House and Senate Public Works committees, which have the final say on new buildings, directed GSA to study consolidation of Queens area Social Security processing operations -- now inefficient and time-consuming in separate buildings not designed for heavy computer use.

Within six months, GSA came up with the plan for a new processing center in Jamaica. Its construction, at federal expense, would mean an end to the rent bills being paid for the separate SSA structures.

That approach appealed for a variety of reasons to Moynihan, who for months has been crusading to reform GSA building policies and put an end to rent-paying by the government.

As chairman of the Senate's informal panel that oversees buildings, Moynihan was in a key spot to strike a blow for reform (no more rent) and get a new building for his state. His reforms, incidentally, also would remove building-approval powers from the panel he heads.

On the House side, Addabbo had worked for years to convince the House Public Works Committee of the merit of a new building in his home district.

Addabbo also is the No. 2 Democrat on an Appropriations subcommittee that voted last Monday to authorize GSA to use money from its public buildings fund to proceed with the Jamaica facility.

But before the plan ever reached the congressional voting stage, the Lefrak Organization, owner of two of the leased buildings, was squirming.

Lefrak would be losing a guaranteed tenant, even though the firm contended it was losing money with the yearly rental rates of about $3 million GSA was paying. Faced with that, Lefrak came up with a plan.

The organization offered to sell its two buildings, renovating them to Social Security specifications, for $42 million. Lefrak's idea was that everyone would benefit -- no costly new federal building, no more rents, no dislocation of SSA employes, no disruption of the Corona-Elmhurst neighborhoods.

But as Richard Lefrak, president, and his agents tell it, they couldn't get the time of day from GSA. Lefrak said GSA would not even consider his offer to sell.

Lefrak hired a law firm and a public relations firm in Washington to help him agitate and find sympathetic ears in Congress. The agitation got him a hearing, but few sympathetic ears.

"Thus far," he said, "GSA has treated our offer as though saving money might be a contagious disease."

James Whitlock, an assistant GSA commisioner for public buildings, told the Moynihan panel that GSA hadn't asked Lefrak for an offer and saw "no reason to analyze his proposal because it wouldn't suit our long-range needs."

Sens. Simpson and Stafford were, as Simpson put it, "appalled when we find we have disregarded a proposal that could save from $40 million to $60 million."

Then, turning to Moynihan, he said: "You have all the horses. I'd like to know why GSA didn't feel compelled to study all the alternatives. Sens. Ed Muskie and Henry Bellmon fight over $10 million in the Budget Committee and over here, $60 million slops all over the stove."

Moynihan didn't answer that, but he did have the horses. Pulling five proxies from his pocket, he won 7 to 3, giving Jamaica the green light.