An influential member of the United States Olympic Committee (USOC) said yesterday that there is growing support within the organization for sending a U.S. team to this summer's Olympic Games in Moscow despite President Carter's request for a boycott.

"I have the impression that the mood of the country and the mood of the USOC is changing because of the lack of support from other countries," Robert Helmick, a Des Moines attorney who is president of the Amateur Athletic Union and has been on the USOC since 1972, said in an interview with United Press International.

"This changing mood has been intensified by some of the statements out of the White House last week saying the decision has been already made," Helmick said.

"We don't like the posture of the White House that it's a decision of the private sector and, at the same time, them telling us that the decision has already been made. It would be quite appropriate to simply have the president make a pronouncement that he is forbidding U.S. citizens from going to Moscow," Hemlick said.

The USOC, which was formed by an act of Congress and could be dissolved the same way, is a private organization which has coordinating authority over amateur sports in the U.S. American athletes can be entered in the Olympics only by the USOC, which according to Olympic rules represents the United States in all matters pertaining to the Games.

The president has no statutory authority to order the USOC to decline its invitation to Moscow, though he has considerable political leverage. Justice and State Department sources said it is not clear exactly what legal authority, if any, the president has to limit travel to the Soviet Union by individual citizens, but that he could dclare a national state of emergency and prohibit all travel by Americans to the Soviet Union during the period of the Olympics.

Hemlick said he supported the president's position initially and introduced a resolution to the USOC Executive Board in January calling for the U.S. not to participate in the Moscow Games because of the Soviet invasion of Afghanistan.

Subsequent events, including resistance to a boycott by other national Olympic committees, have led him to conclude that U.S. nonparticipation would be ineffective in punishing the Soviet Union, however, and instead would most penalize the atheletes of boycotting nations, Hemlick said.

The USOC's House of Delegates will consider the invitation of the Moscow Games at its meeting in Colorado Springs, April 11-13. Helmick said he will work for deferring a final decision until the May 24 deadline for submitting Olympic entries.

"I personally feel we should wait until the very last moment. Then, in the American tradition, we may very well differ with the president," Helmick said.

"I see no reason, if the boycott is not going to be effective, for singling out the athletes to be forfeited for this. If we severed all relations with Russia, that would be quite a different question. When it's only athletes, then I get very concerned."

USOC President Robert J. Kane, asked to comment on Helmick's statement, said: "I think that if nothing else it demonstrates that the USOC is not a monolithic organization. We have people who think for themselves, and this is a point of view -- a very strong point of view -- by one of our most thoughtful members.

"However, there are differing points of view on this matter, and the USOC position will be taken on April 12-13, when the House of Delegates meets," Kane said.

The USOC issued a statement on Feb. 14 -- after the International Olympic Committee (IOC) rejected its proposal that the Games be moved from Moscow, postponed or canceled -- saying it would "accept any decision concerning our participation in the Games the president makes in view of his analysis of what is the best for the country."

When Soviet troops were not withdrawn from Afghanistan by the Feb. 20 deadline set by the president, the administration said that its decision against U.S. participation in Moscow became "final and irrevocable."

President Carter reiterated the point in a speech to Olympic athletes and their elected representatives at the White House last week.

The British Olympic Association voted Tuesday to "accept forthwith" its invitation to Moscow, however, despite the opposition of Prime Minister Thatcher and a majority of Parliament.

Kane emphasized that he does not expect the USOC to "defy" the president, but said he does not expect the House of Delegates to vote next month to decline the invitation to Moscow, as the president has requested.

Kane said that recommendations made by the USOC's Athletes Advisory Council last weekend -- calling for U.S. athletes to participate in Moscow, but to protest Soviet aggression be refusing to participate in opening, closing, and medals ceremonies and by staying outside the Soviet Union except during their events -- "Ought to be explored."

"These ideas for protest would seem to be more precisely directed against the Soviet Union than boycotting the Games, which belong to the IOC and not to Moscow," said Kane, adding that "the athletes' point of view seems to be gaining more support among our membership."