Seldom does the president have the opportunity to pick up the telephone and save the American taxpayers $744 million. President Reagan has precisely that opportunity this week. Unless he does so, the U.S. Synthetic Fuels Corporation is sure to spend that money.

On July 31, the House voted by a 3-to-1 ratio to close down the problem-plagued Synthetic Fuels Corporation. The House decision reflected a recognition of dramatically changed energy and economic conditions and a heightened frustration with the continued administrative bungling of the corporation's managers. The massive synthetic fuels commercialization program initiated under the Energy Security Act of 1980 fell victim to the present-day realities of falling oil prices, rising synfuels production costs and gargantuan federal deficits. Unsurprisingly, the House acted decisively to prevent the SFC from squandering its $7.9 billion slush fund on more uneconomic subsidy-starved white elephants. The Senate, however, has not acted, and does not intend to do so for some time.

But the SFC board of directors intends to act and act quickly. With the writing on the wall, the board announced plans to sign contracts for three synfuels projects by the end of September. The output of the proposed projects: 13,0000 barrels of oil a day, a drop in the bucket. The price tag for the taxpayers: $744 million.

Most revealing of its desperate plight is the SFC board's announced intention to reward the Union Oil Co. with an additional $500 million in loan and price guarantees for its inoperable oil shale failure in western Colorado. Delayed more than 1 1/2 years by technical problems, the 10,000-barrel- a-day facility has been unable to run continuously for more than 30 hours at a time. It is characterized by one SFC director as a "technological dry- hole," and has has been placed on standby for five months while Union's engineers huddle around the drawing board.

But the SFC board doesn't have five months. Undeterred by technical uncertainty, the board has decided to reward Union's failure by increasing its current $400 million federal contract an additional half-billion dollars in government subsidies. Good news for Union Oil, which is currently concerned with refinancing the $4.2 billion of debt needed to fight off T. Boone Pickens recent takeover attempt. Bad news for the American taxpayer, who has to pay Union Oil the difference between the $67-per-barrel price guaranteed by the SFC and the prevailing market price of oil, $27 per barrel and declining.

And whom do they intend to convince? An internal SFC document ("The Plan") recently surfaced outlining the corporation's strategy for securing enough Senate votes to avoid extinction. The document lays out a lobbying blitz that will "hold" and "leverage" senators by advancing projects located in their home states. While federal agency lobbying on Capitol Hill may be commonplace, the SFC has reached new heights of effrontery in its crude efforts to buy votes and time.

Only one person can stop the SFC from squandering more of the taxpayers' money. Along with several House colleagues, I recently wrote the president and asked his help. We explained that we in the House had done all we could, and the Senate would act soon. In the meantime, hundreds of millions and potentially billions of dollars are going to walk out the door. Accordingly, the White House Domestic Policy Council put a hold on the SFC spending spree until the president reviewed the matter personally.

Thus far the Oval Office has remained ominously silent. It's difficult to believe that while the deficit grows and Congress grapples over spending priorities, the president could allow the Synthetic Fuels Corporation to spend the taxpayer further into debt. One telephone call from the president to his appointees at the SFC could change all of this. Mr. Reagan, it's time to pick up the phone.