One month after President Carter's rescue mission blew up in the desert, U.S. strategy toward Iran is again moving down the same track that twice before led to humiliating rebuffs -- a long-shot search for a diplomatic formula capable of ending the hostage crisis.

That is the policy inherent in the calls by the new secretary of state, Edmund S. Muskie, for a "carrot-and-stick" approach combining the pressure of economic sanctions with a probing for new channels of communication with the revolutionary leaders in Tehran.

Muskie has undertaken this effort under circumstances so lacking in promise of quick results that there are serious questions about whether the administration actually has a strategy or has simply bogged down in wheel spinning and Micawberish hopes that "something will turn up."

Still, administration officials insist they have reasons for hoping that this time round the resort to diplomacy will prove more successful than it did in earlier stages of the seven-month-old hostage crisis. And, in an effort to buy some maneuvering room for Muskie, the administration has tried to put the situation on the back burner of public attention by ceasing to treat it as a major crisis.

However, while there are some new wrinkles involved, Muskie's "carrot-and-stick" is essentially the same policy that his predecessor, Cyrus R. Vance, was pursuing prior to the illfated April 24 attempt to wrest the hostages from captivity by force.

One U.S. official, describing the Muskie approach, noted: "Throughout all the various phases of the crisis, our response has been an alternating of the carrot and stick, with one or the other predominant at different stages. As the carrots get eaten up or the sticks get broken, we've had to change our tactics in recognition of the realities of the moment."

"Right now," he added, "we're at one of these moments. Things aren't as they were before April 24. When the rescue attempt failed, we lost the opportunity for a quick resolution. Now we've had to turn back to a more long-range course and hope that patience and mounting international pressure on the Iranians eventually will lead to some kind of negotiated solution."

On the surface, though there seems to be little hard evidence that quiet diplomacy will be any more effective than the past attempts to find a solution acceptable to those factions in Iran's divided power structure fighting each other for control of the Iranian revolution.

On two previous occasions -- first through the intermediary offices of a United Nations commission and then through a more direct approach to the moderate forces led by President Abol Hassan Bani-Sadr -- the United States invested considerable prestige in trying to work out elaborate deals to get the hostages transferred out of the hands of their militant captors.

Both times, however, just as the deals appeared to be clicking into place, they collapsed because the combined opposition of Iranian leftists and clerical rightists blocked Bani-bined opposition of Iranian leftists and clerical rightists blocked Bani-Sadr from keeping his end of the bargain. a

At present, the internal Iranian power struggle appears to be tilting in favor of the same forces that scuttled these earlier initiatives. And the drumfire of anti-American rhetoric and demands that the hostages be subjected to spy trials continuing to pour from their ranks hardly seems conducive to the idea that they might be receptive to new negotiations.

Nor does the "stick" side of the Muskie approach seem very promising at the moment. It is embodied in the effort to enlist. America's principal industrial allies in clamping a vise of economic sanctions on Iran, but the much-publicized foot-dragging with which the allies have responded has raised serious questions about whether the sanctions will have much practical or symbolic effect.

Still, U.S. officials insist that the outlook isn't necessarily as bleak as it seems. While conceding that the United States was disappointed by the allies' insistence on watering down the sanctions, these officials contend that the measures are substantial enough to keep causing hardships and dislocations in the Iranian economy.

"No one has ever pretended that sanctions by themselves would bring Iran to its knees," one senior official said. "Instead, they have to be seen as part of a slow, psychological grinding-down process aimed at increasing the Iranian sense of isolation and making life there more difficult so that people gradually will become more receptive to the idea that the satisfaction of holding the hostages isn't worth the price they're paying in economic discomfiture."

But while the administration continues to make public obeisance to the importance of sanctions, U.S. officials privately admit they are less important to Muskie's calculations than his emphasis on a renewed diplomatic offensive. In that area, the officials say, there are elements in the current situation that they intuitively feel may be working to the administration's advantage.

One has been the administration's success, at least for the moment, in deflecting the attention of the American public away from the hostage issue so that for the first time Carter and Muskie can try to chip away at the crisis in slow, step-by-step fashion without having to pacify public frustration through dramatic gestures.

The raid, for all its spectacular failure, seemed to have lanced a boil imbeeded deep within the national consciousness that had been building up pressure for military action. In its aftermath, the president, the public and the press seem to have been moving, almost by tacit consensus, to push the hostage issue out of the dominance it has held over the nation's attention span for so many months.

Another consideration that U.S. officials regard as very important is the fact that the raid, costly as it was in terms of American lives and expectations, did not have the effect that many initially feared would be the greatest price for failure -- an international loss of respect for the reach and weight of American military power.

Instead, they say, the available evidence indicates that the raid jarred a number of governments into taking a hard new look at the lengths to which the United States might go if provoked too far and to start worrying about the situation's potential for escalating into future military actions that could pose a runaway threat to world peace.

According to the officials, this changing attitude already is evident in Iran, where, as one U.S. strategist puts it, "The dominant attitude prior to the raid was that they could push us around at will and that we'd never respond militarily."

In addition, the officials contend, there is now an uneasy awareness among many other potentially affected countries -- America's European allies, the Soviet Union, and the nations of the Moslem world -- that if the wheel does spin around again to where Washington feels compelled to reconsider its military options, there's likely to be much more involved next time than a small-force rescue operation.

Because some of the hostages have been taken out of the U.S. embassy compound in Tehran and scattered around Iran, the concept of another quick, in-and-out rescue raid is no longer practical. Instead, any future U.S. military action would involve an escalation to punitive steps such as a naval blockade and would carry with it the risk of other countries being sucked into the conflict.

Muskie has gone to great lengths to telegraph that the United States is not contemplating any such actions at this time. But, U.S. sources say, the awareness that these options remain in the background is causing a growing consensus in the international community that the interests of everyone require a resolution of the U.S.-Iranian confrontation.

As a result, one official noted, "The last month has produced a situation where it seems like almost half the governments in the world have been lining up with offers to try and play an intermediary role between us and Iran."

Among those known to be seeking a go-between role are the West Europeans, various Moslem governments and the United Nations. Although U.S. sources acknowledge that a number of behind-the-scenes initiatives already are under way, they are reluctant to discuss specifics because they stress that all are still in a very preliminary exploratory phase, and it is far too early to gauge which will run into dead ends and which might show signs of leading somewhere.

The process, the sources stress, is going to be torturously slow and circuitous, but the hope is that eventually some of these probes will strike a responsive chord in Tehran and force open a new negotiating channel that will be more effective than those tried in the past by involving not only Bani-Sadr's moderate faction but also the hardliners led by Ayatollah Mohammed Beheshti.