U.S. officials are known to be concerned about preserving the American-Jordanian relationship in the aftermath of the collapse of talks on President Reagan's Middle East peace initiative.

They are understood to be particularly anxious to protect King Hussein from being made a scapegoat in the failure of those efforts.

Those U.S. interests appear to explain, at least in part, the reason for the stark differences in assessments here and in Washington about the prospects for reviving the peace plan soon.

There appears to be a genuine desire to maintain the Reagan initiative as a framework for future efforts. Also, there are still faint hopes that Hussein's Sunday declaration terminating talks with Palestine Liberation Organization Chairman Yasser Arafat on the Reagan plan might have shock value and cause moderate Arab states to support a new effort.

It is understood, however, that the point has been driven home to Reagan that Hussein himself intends now to "hunker down" and wait to see what Saudi Arabia, the PLO and the United States do.

There is said to be strong appreciation by the Reagan administration for what they see as Hussein's "artful" performance in trying to get an agreement with Arafat to enable the king to join talks based on Reagan's initiative. The administration also is said to understand that once Arafat declined to do so, Hussein could not take the large risk of breaking ranks with fellow Arabs and enter talks alone.

It is understood that the upbeat statements now coming out of Washington about the efforts were carefully constructed, at least in part, to credit Hussein with a strong effort and ascribe the failure to radical PLO factions bent on dooming the initiative.

Hussein is described here as being relieved at the initial reaction from Washington. Reportedly Jordanians here were concerned that if he did not deliver, the monarchy here would be held responsible.

But the initial signals--Secretary of State George P. Shultz's comments Monday and, before that, Reagan's two telephone calls to Hussein on Sunday, after Hussein had decided to make the statement--have brought a measure of relief.

There is concern here that Congress might be less understanding about why Hussein felt he could not enter negotiations alone with Israel, but some observers say that Jordan's position in Congress would certainly have been eroded if there had been no announcement.

Jordanians and Western diplomats have said that they think Arafat made a strong effort to get his organization to support the initiative, but questions are still being raised here whether he was simply deceiving Hussein about reaching tentative agreement in their intensive discussions.

The document that became the centerpiece of negotiations set forth principles that would have authorized Hussein to enter negotiations but it was not as detailed as previous accounts indicated, knowledgeable sources said here today.

The significance of the document, said one who studied it and was an ardent supporter of the initiative, was in its principles, both explicit and implicit.

This person speculated that PLO leaders rejected it because they understood that if Arafat signed it, the PLO was "not only going to be in the rear seat, they were going back there in the rumble seat."

Jordanians reportedly counted heads when they thought there was hope for beginning negotiations and calculated that 17 of 21 Arab states would be supportive.

It is this putative sentiment on which U.S. hopes for future moves in the context of the Reagan initiative are said to rest.

U.S. officials reportedly hope that the Saudis, whose role is still regarded as "pivotal" might "corner" Arafat and coax him into going along. If not, they hope that Arafat might decide to abandon his consensus-style politics and risk a split within the PLO by agreeing to the peace plan.

A third possibility is that the Arab world might decide that the PLO is now an irrelevancy and withdraw its status as sole legitimate representative of the Palestinians, removing the obstacle Hussein saw when he decided against entering talks alone after failing to reach agreement with Arafat.

There is a strong sense here that Reagan is not going to alter the initiative he announced on Sept. 1, although it is understood that option papers for future diplomatic moves are being prepared by U.S. officials here and in Washington.

Some Jordanians still hope that the Europeans might be helpful in getting the United States to bend a bit on the issues of recognition of the PLO and the right of self-determination for Palestinians on the Israeli-occupied West Bank and Gaza.

The United States has refused to recognize the PLO until it recognizes Israel. The Reagan plan envisions a Palestinian entity linked to Jordan on the West Bank and Gaza while the Palestinians demand a fully independent state of their own.

British Foreign Minister Francis Pym, here briefly today on his way back to London from Saudi Arabia, told reporters he strongly endorsed the Reagan plan.

"The events of the last week do not alter the central reality that there is no feasible alternative to using the Reagan plan despite the reservations which many countries feel about it as the starting point for the peace process," Pym said.