President Carter yesterday blamed the media for an unjustified "buildup of expectations" that Iran is about to release the 52 U.S. hostages, and said that the raised hopes could lead to "bitter disappointment."

Later, at an evening campaign stop in Wyoming, Mich., Carter was asked about news reports that the hostages would be released as early as Sunday.

"We don't have any clear signal from the Iranian leaders about when the hostages will be released," he said. And he reminded his audience in the Wyoming public library that "we've had private messages and also some public statements time after time after time that the hostages were going to be released imminently, soon. We've always been disappointed."

At an earlier campaign stop in Gloucester City, N.J., Carter said during a discussion of the hostage issue: "One thing that concerns me a lot lately has been a buildup in the American press -- television, radio, and newspapers -- of expectations that the hostages are going to come home early that I don't think are justified."

The president's comments punctuated a day in which the government vibrated with rumors and counterrumors concerning the hostages.

Speculation in Washington yesterday centered on the possibility that the Iranians might release some of the hostages, holding military personnel or those accused of being CIA agents.

According to some versions of this speculation, the Iranians would conduct a pro-forma trial of the remaining Americans and then expel them.

Meanwhile, the relatives of the captive Americans held their breath or made cautious plans for reunions with their loved ones, in hopes that the ordeal might end short of its impending one-year anniversary.

Vice President Mondale yesterday morning warned against undue optimism, and emphasized that no negotiations are taking place between the United States and Iran. In an interview on NBC's "Today" show, Mondale said the United States has kept careful track of frozen Iranian assets, "so that should they [negotiations] proceed, we're ready to move without any delay."

And Rosalynn Carter added her voice to the cautionary chorus, vowing that the United States will not make any "embarrassing" concessions to win release of the hostages.

"We have to always preserve the integrity of our country," she told a news conference in Milwaukee. She added that she considers it "immaterial" whether release of the hostages will help her husband win a second term.

"It's not political," she said. "If we were going to do it for political purposes we would have done it a long time ago."

The Iranian parliament is still expected to take up its examination of the hostage issue Sunday, but beyond that, "we stand exactly where we stood yesterday," reported State Department spokesman John Trattner.

Officials have been saying for more than a week that the war between Iran and Iraq seems to have given new impetus to a drive in Iran for settlement of the hostage issue.

Meanwhile, the attention of some of the families has turned irresistably to the details of any possible homecoming.

While most say that they will continue to resist getting their hopes up only to have them dashed again, and that they are making no special plans, the family of hostage Richard H. Morefield has taken initial steps to plan a celebratory Thanksgiving mass for him.

His wife, Dorothea Morefield of San Diego said she intends to go to West Germany to rejoin her husband. The hostages are expected to be sent immediately to Weisbaden after their release.

The question of how quickly where and at whose expense the families will be permitted to join their hostage relatives has become a source of some irritation and confusion, according to some of the wives, in part because the State Department is discouraging them from making the trip to join their husbands, and is not offering to pay for a group flight.

Contingency plans call for the hostages to be flown to the large U.S. hospital facility in West Germany for at least a week before they return to the United States, Pentagon and State Department officials confirmed yesterday. The hostages would then be reunited with their families at an undisclosed location in the United States. But they cautioned that the situation contains too many unknowns to be sure those plans will be followed.

Several family members have been offered the price of their air fare to Europe by reporters or other media representatives in return for exclusive stories, according to Louisa Kennedy, wife of hostage Moorhead Kennedy Jr., and other wives.

"Once again, the families are being used by the media," said Kennedy, who speaks for the group that represents the families. "I find this very discouraging."

Barbara Rosen, wife of hostage Barry Rosen, was planning a trip from New York, where she is staying with her parents and two children to Florida next week. But now, because of the rumors, she said, "I don't know what my plans are."

Though she is still skeptical, she said, recent developments seem "more significant than anything that's happened in the past," because they are being initiated by the Iranians.

Asked the low point of the year-long ordeal for her personally, she said, "It may turn out to be this weekend. . . ."