The United States Olympic Committee (USOC) voted by 2 to 1 today to accept President Carter's demand that the United States boycott this summer's Olympic Games in Moscow.

By a 1,604-to-797 vote, with two abstentions, the USOC's House of Delegates decided not to send a team to the July 19-Aug. 3 Moscow Games unless the president changes his position and approves the participation of U.S. athletes before the May 24 deadline for Olympic entry.

In Washington, White House press secretary Jody Powell said the president "welcomes the strong vote" of the USOC not to send an Olympic team to Moscow "in light of his advice that to send a team would be contrary to our national interest."

Powell added however, "The president has authorized me to say that this advice will not change by May 20 or at any time thereafter.

"Now that the USOC has made clear that it will not participate in the Moscow Games," Powell said in a statement, "we are confident that other leading nations of the free world will join in this demonstration that no nation is entitled to serve as host for an Olympic festival of peace while it persists in invading and subjugating another nation."

Today's vote, the first time the USOC has rejected an invitation to the Olympics, was a major victory for the Carter administration in its campaign to protest the Soviet Union's invasion of Afghanistan.

The House of Delegates also voted against the organization of so-called "alternative games," which the Carter administration had vowed to see developed.

USOC Executive Director F. Don Miller said that athletes and national governing bodies felt there "is no substitute for the Olympic Games" and voted "by a vast majority" to reject the proposal for alternative games.

White House counsel Lloyd Cutler said such makeshift competition had been proposed for the athletes' benefit, and "if this is something that the athletes and national governing boards don't want, that would resolve the issue."

The ballot by the USOC's 275 delegates, most of whom cast multiple votes apportioned according to the sports organizations they represent, came six hours after Vice President Mondale addressed the meeting.

Mondale called the boycott vote "truly a referendum on freedom" and said, "What is at stake is no less than the future security of the civilized world . . . if we and our allies and friends fail to use every single peaceful means available to preserve the peace, what hope is there that peace will be long preserved?"

The vice president's speech was the administration's final argument in an intensive two-week campaign to lobby USOC delegates into voting against sending a team to Moscow.

President Carter said Thursday that he would take legal action if necessary to ensure that U.S. athletes do not participate in the Moscow Games.

In the wake of such heavy administration pressure, which some delegates found distasteful, the USOC adopted a resolution stating:

"Since the president of the United States has advised USOC that in light of international events the national security of the country is threatened, the USOC has decided not to send a team to the 1980 Summer Games in Moscow, but the United States Olympic team shall be selected in the usual manner in order to recognize the athletes who have been in training as Olympians.

"Be it further resolved that if the president of the United States advises the USOC on or before May 20 that international events have become compatible with the national interest and the national security is no longer threatened, the USOC will enter its athletes in the 1980 Games."

These are the events the U.S. team would have entered: archery, basketball, biathlon, boxing, canoeing/kayaking, cycling, diving, equestrian, fencing, field hockey, gymnastics, judo, pentathlon, rowing, shooting, soccer, swimming, team handball, track and field, volleyball, water polo, weightlifting, wrestling and yachting.

Two other resolutions were also debated, however.

The first was an earlier administrative committee resolution, approved March 8, which recommended the USOC defer a final decision on the invitation to Moscow until May 20, and resolved that the USOC would send a team to Moscow unless the president expressly stated that to so would compromise the national interest and security.

The third resolution considered by the delegates was drafted by a group of athletes and urged "that USOC accept the invitation to participate in the 1980 Olympic Games."

Two other resolutions were proposed from the floor but quickly rejected by voice vote before serious discussions of the three major resolutions began in the closed session at the Antlers Plaza Hotel here.

The first, characterized by one delegate as a "rather rude, crude and blunt message to the president to go to hell," was rejected "decisively," according to the USOC's Miller.

Another, understood to be an amendment chastising the Carter administration for allegedly heavy-handed lobbying tactics, also was rejected out of hand, according to USOC president Robert J. Kane.

On Friday, it appeared the delegates would vote quickly to adopt its administrative committee's revised resolution that the USOC not send a team to Moscow unless the president gives his blessing.

But this resolution reportedly received a hostile reception at a Friday night meeting of representatives from the national governing bodies of the 32 sports on the Olympic and Pan American Games programs.

Delegates from these organizations cast 71 percent of the 2,403 votes in the House of Delegates.

The reluctance of the national governing bodies apparently caused alarm among USOC officers and the executive leadership, who generally believe that defiance of Carter's demand would bring public relations and financial ruin to the USOC. This morning there seemed to be a shift of some delegates toward not making a final decision at today's meeting. The USOC is an organization inclined toward indecision, and given to recapturing caution from the wind.

Most delegates willing to comment on Mondale's speech said they found it eloquent but would have preferred a softer approach -- a fireside chat rather than the ringing denunciation of the Soviet Union that Mondale delivered.

Mondale reviewed the other economic, political and military steps the United States has taken to underscore its condemnation of Soviet aggression in Afghanistan. He then said "the president, the Congress and the American people understand that a world which travels to the Moscow Games devalues its condemnation and offers its complicity to Soviet propaganda.

"I am convinced that the American people do not want their athletes cast as pawns in that tawdry propaganda charade. And I urge you to respect that undeniable consensus."

Mondale said the administration recognizes the sacrifice it was asking from athletes and sports officials.

"But on behalf of the president of the United States," he said, "I assure you that our nation will do everything in its power to ensure the success of the [1984] Los Angeles Games; to help the Olympic Committee restore its finances; to provide even greater assistance to the development of amateur sports, and, above all, to recognize the true heroism of our athletes who do not go to Moscow."

The USOC's Miller acknowledged the group has had recent discussions with the administration on federal financial assistance.

The USOC's fund-raising has dwindled since the president proposed a Moscow boycott Jan. 4, and the organization is facing a projected $7 million deficit by the end of the year.

In related developments, attorneys for the San Francisco-based Lawyers Committee for Sports Freedom circulated copies of a Hypothetical lawsuit" which they said they would file as a class action on behalf of prospective Olympians denied the opportunity to compete in Moscow.

West German Chancellor Helmut Schmidt said at a political rally today in Germany that Soviet presence in Afghanistan would make West German participation in the Moscow Games impossible.

"The conditions for participation are not present. There is not much more time for the Soviet Union to make this possible," Schmidt said, noting that the German Olympic Committee will decide about going to Moscow May 15.