If President Carter expressly states that U.S. participation in this summer's Olympic Games in Moscow is contrary to the national interest and security, it is highly unlikely that the United States Olympic Committee (USOC) would try to send a team to Moscow.

"If the president determines at the time Olympic entries are due that our participation would be detrimental to the national interest and security, I'm certain that as good Americans we would respect that. I think we all recognize that the president of the United States is the one who must make that decision," USOC Executive Direct F. Don Miller said last week, in response to the suggestion by one influential member that the USOC might vote to send a team to Moscow in disregard of the president's request.

Miller emphasized, however, that the USOC has not yet made a decision, even if President Carter has.

Under the rules of the International Olympic Committee, which runs the Games, the decision to attend must be made by the country's national Olympic committee -- the USOC, in this case -- and not by the government.

Any political interference by the government could lead to expulsion from the Olympics.

Statements by USOC officers in recent months that they would abide by the president's decision are not binding on the 482-member House of Delegates, the USOC's policy-making body, which is expected to vote on the matter at its April 11-13 meeting in Colorado Springs.

Indeed, in the past few weeks, there has been growing sentiment by the 32 national governing bodies of the Olympic sports to field a team in Moscow in defiance of the president's request.

The administration, apprehensive about the shifting opinion, has intensified its lobbying of the governing bodies, which would compose the controling bloc on a boycott vote next weekend in Colorado.

It is probable the House of Delegates will not decide to accept or reject the U.S. invitation to the Moscow Games. Constitutionally, it can and probably will empower a smaller group -- the USOC officers or Administrative Committee -- to make the decision in May, based on world conditions and the attitude of the White House in the days immediately before the May 24 deadline for Olympic entries.

Meanwhile the invitation -- a single sentence printed in three languages (French, English, Russian) and signed by Ignati T. Novikov, president of the Moscow Olympic Organizing committee and a high-ranking Kremlin official -- sits atop a stack of papers in a rear corner of Miller's desk in Colorado Springs.

"Entries are not due until May 24, and we see no reason to make a premature decision," Miller said with a wry smile, fingering the document that represented nothing but a routine formality until Carter first proposed an Olympic boycott on Jan. 2. "I keep it in sight so that I don't forget about it."

Little chance of that, since the agonizing decision of whether -- and when -- to reject the invitation has thrust the USOC and the Olympic movement into unprecedented conflict.

The Carter administration insists that the decision not to send an American team to Moscow because of the Soviet invasion of Afghanistan became "final and irrevocable" on Feb. 20. That was the deadline initially set by the president for the Soviets' "full withdrawal" from Afghanistan.

Carter personally buttressed prior hard-line statements by his aides during a resolute, impassioned speech to U.S. athletes and their representatives at the White House last month.

"I can't say at this moment what other nations will not go to the summer Olympics in Moscow. Ours will not go," the president said, his voice firm and uncompromising. "I say that with not any equivocation. The decision has been made."

Last week, the president ordered a ban on the export of all goods and technology earmarked for the Moscow Games, except medical items. He prohibited further Olympic-related transactions and payments, including NBC's shipment of broadcast equipment to Moscow and payment of the remaining $20 million of its $87 million commitment for broadcast rights and facilities.

At the same time the White House issued a statement -- apparently for the benefit of USOC skeptics -- which termed the Soviet occupation of Afghanistan "an unusual and extraordinary threat to the national security, foreign policy and economy of the United States."

Informed that USOC officials were of the opinion that Carter never actually had said that American participation in Moscow would be detrimental to national security, Lloyd Cutler, presidential counsel, said they had never raised the issue in that context. But Cutler reminded that the president had duly informed the USOC of his decision that participation in Moscow was inconsistent with the national interest.

"I don't think the phrasing makes much difference. The president has said over and over again how he regards the invasion of Afghanistan as affecting our national security," Cutler said. "We expect the USOC to do what its officers have said it will do."

Assuming his position does not change -- and politically, that seems as certain as anything can be in an election year, because the boycott is one of the few issues on which Carter is perceived to be tough and decisive -- the USOC appears certain to comply eventually with the president's request.

There are two reasons for this. USOC members are "good Americans first," as Robert J. Kane, the organization's president, puts it. Moreover, the USOC is facing a budget deficit in the neighborhood of $7 million for the four-year period ending Dec. 31, mostly because of revenue losses caused by the boycott prospect.

The USOC will seek a subsidy from the federal government to cover at least part of this projected shortfall, and can scarcely afford the further curtailmenet of private and corporate contributions that would almost surely be the consequence of defying a presidential decision not to participate in Moscow.

Especially since the president's position has been supported by near-unanimous resolutions in both houses of Congress and has the backing of a majority of the American public, according to opinion polls, the USOC knows that defiance would be tantamount to inviting fiscal ruin.

Nevertheless, feeling a deep responsibility to the athletes it represents, the USOC continues to grasp at straws, and to keep the door to Moscow propped open with them.

Officials know they have some leeway with the administration, which had asked for a "prompt" rejection of the Moscow invitation, because the White House has discovered it needs the USOC to help organize the "post-Olympic, world-class games" it has promised American athletes and the government of countries it is trying to enlist in the boycott.

The administration even has stopped calling these "alternative games" or "counter-Olympics," in deference to the USCO's position that it will not be a party to any competition compentitive to the Olympic Games or that would erode their significance. The USOC has agreed to help organize a "meaningful international experience for our athletes if they don't go to Moscow," and to seek the necessary approvals for such games from the international sports federations affiliated with the International Olympic Committee (IOC).

Meantime, the USOC continues to "hope against hope for a miracle," as Kane puts it -- namely, a Soviet troop withdrawal from Afghanistan that might affect a shift in U.S. public opinion and prompt a reelection-minded Carter to change his position.

A confidential resolution adopted by the USOC Administrative Committee on March 15 reportedly recommends to the House of Delegates that the Moscow invitation not be formally rejected until the week of May 24, and then only if the president makes a statement that U.S. participation is not consistent with the national interest and security.

"I think that's the key to it. In our judgment, the president never has actually said that sending a team to Moscow compromises national security," Miller said last week, after Robert Hemlick, Des Moines attorney, president of the Amateur Athletic Union and influential USOC member, suggested that the USOC might "in the American tradition . . . very well differ with the president."

Kane called Helmick's comments "a very strong statement by one of our most thoughtful members," and said he hoped there was still room for compromise. He said recent proposals made by the USOC's Athletes Advisory Council and the national Olympic committees of several European nations, calling for protests against Soviet aggression while participating at Moscow, "ought to be explored."

The athletes and Olympic committee representatives suggested boycotting opening and closing ceremonies and medals presentations, and perhaps having athletes stay away from the Olympic village and quarter outside the U.S.S.R. except for the period of their events, as means of protest that would sting and embarrass the Soviets without unduly penalizing the athletes who have trained for years.

"These measures would seem to be a more appropriate way of protesting Soviet aggression without boycotting the Games, which belong to the IOC and to Moscow," said Kane. "This point of view seems to be gaining support among our members."

The Carter administration rejects the proposal.

"It's not acceptable. It is no substitute for a decision not to send a team," White House counsel Cutler said in an interview with The Washington Post last week. "What undoubtedly would happen is that there would be no opening and closing ceremonies, maybe no medals or other ceremonies, and the net effect would be simply that you have more sports and less festival. The impact of the protest would be entirely lost.

"Besides that," Cutler added tersely, "the IOC rules forbid any kind of political protest."