Jordan's King Hussein is agonizing over what he calls the most serious crisis in his checkered 26 years on the Hashemite throne.

Courted and pressured by forces as disparate as his American allies and his former Palestinian guerrilla enemies, the king faces a thankless task that many of his subjects believe will result in his being damned if he does and damned if he doesn't. He is being to participate in negotiations on the future of the Israeli-occupied West Bank which Jordan ran, not entirely comfortably, for 19 years before the 1967 Arab-Israeli war.

A quintessential survivor in the violent politics of the Middle East. Hussein at 42 gives the impression of having been genuinely shocked by what he regards as cavalier behavior by the Egyptians and Americans at Camp David.

He was not consulted, and probably with good reason, for he has made it increasingly clear that he will not buy the Camp David provisions for the West Bank in their present form.

Yet, simply staying out has its own disadvantages. The king would like to recover the West Bank territory lost when he joined the 1967 war. Whatever his disclaimers, he may well want to keep the West Bank if it is freed from Israeli occupation. And perhaps he should be taken at his word when he says it is his duty to help the Palestinians achieve their national rights on the West Bank.

The king's final decision, in the words of one of Jordan's most astute politicians, "will tip the balance toward a comprehensive Mideast settlement or a separate Egyptian-Israeli peace, with all the dangers that entails."

The choice is not easy. And the euphoria occasioned by the Camp David agreements - especially in the United States - leave him and most Jordanians perplexed and worried.

Barring an unforseen change of heart. Hussein shows no interest in accepting his proffered role in the West Bank negotiations without a much broadened American public commitment and key Arab backing from at least Saudi Arabi and Syria.

He wants a written, public American commitment according to informed Jordanian and foreign sources, about total Israeli withdrawal from occupied Arab territories, especially Arab Jerusalem: a comprehensive peace settlement involving Syria, as well as other bedrock points.

And Jordan wants the United States physically present in any negotiations about the West Bank - just as it was in the Camp David talks. After 11 years of Israeli ploys and encroachments, the Jordanians want the Americans present to insure impartiality and justice.

Whether President Carter is prepared to pay such a price - or whether Israel and its powerful friends in Congress would go along - is far from assured. The Jordanians, like many other Arabs, increasingly question whether the United States can deliver when it comes to Israel.

"We see you giving Israel more arms, money, technology, vetoing anti-Israel resolutions in the United Nations," a prominent former minister said, "and always you tell us it's to make the Israelis more malleable."

Given such doubts. American efforts to win the king over have failed so far in part because Hussein shows little inclination to take the plunge and trust in American promise of support.

This unwillingness to take chances is in part based on disillusioning experiences with Israeli occupation of the West Bank. But tribal tradition also has influenced political mores, especially in this nation swayed by the desert code of its bedouin rulers.

Traditionally, bedouin conflicts are not resolved through negotiations but passively when the aggrieved party is given a peace offering.

"In Arabic there is no phrase per se for making peace," a politician said. "Instead, you arrange 'solh," or conditions which lead to a state of peace. Reconciliation is probably the nearest approximation in English."

Even without such a heritage Jordan faces dangers and constraints - domestically as well as abroad. Within the kingdom's East Bank, roughly half the population is Palestinian and keenly interested in the fate of the Palestinian West Bank and East Jerusalem. The city was reunited and its Arab sector annexed by Israel in 1967.

The king's dilemma is topic "A" with both the political elite and everyday Jordanians trying to shift through the confusion. In a country without elected leaders, public opinion is hard to gauge. Those passionately opposed to Hussein's involvement in negotiations appear limited to the dyed-in-the-wool bedouins who want nothing to do with the West Bank and Palestinians close to the Palestine Liberation Organization.

An apparent majority is tempted by the chance to end Israeli military occupation and stop the creeping Israeli colonization that eats away at the Arab character of East Jerusalem and the West Bank.

More than a generation of Arab naysaying has convinced many Jordanians that the Camp David deal represents a chancy, but worthwhile risk. "It's a girl," one Jordanian explained meaning better than nothing in the Middle East where boy babies are more highly prized.

An astute minister said privately that at least the idea of direct negotiations with Israel over the West Bank is now acceptable. Othe politicians and diplomats are convinced, however, that the king will have to make a major domestic political effort to win backing from such key sectors as the army, notables and professional classes.

Those opposed to negotiations aruge that Jordan has no chance of obtaining Justice against the all-powerful Israelis and point to what they consider Egyptian President Anwar Sadat's "surrender" at Camp David as proof.

"You cannot talk peace unless you prepare for war," a retired colonel said, "and Israel won't be reasonable at any negotiations unless it knows we can inflict 100,000 casualties in the first week." But with Egypt out of the Arab lineup such hopes seem increasingly distant.

Syria and Jordan now face the reality of their three-year-old nightmare - the full brunt of the vastly superior Israeli forces. The Syrian army, weakened by its quagmire role in Lebanon, where Israel exerts pressure at will through its Christian allies, is further undercut by the potiental of Iraqi problem-making.

Were Jordan to join the West Bank talks and leave Syria in the lurch, Damascus could easily unleash the Palestinian guerrillas, whom it controls in Syria and Lebanon. Infiltrators into Jordon could attack targets here and in Israel and bring about the kind of retaliation so blissfully absent since the last guerrillas in Jordan were defeated in the 1970-1971 fightig.

At rock bottom, Hussein needs Syrian passive acceptance - or absence of agressive hostility - if he is to join any West Bank talks. The best way to achieve that is to pressure the United States into obtaining some kind of promise about the Golan Heights, which Syria lost to Israel in 1967.

Nor are Jordan's relations with Saudi Arabia those of a free agent.

The Saudi leadership with its oild money, is conservative and wants to straddle the increasing cleavage in Arab ranks.

Theoretically, Saudi Arabia could be expected to advise Hussein to avoid involvement in West Bank talks, especially since Riyadh is incensed about the absence of any meaningful mention in the Camp David documents of East Jerusalem and its holy places dear to the deeply Moslem Saudis.

But given the Saudi rulers' fear of any gain in Communist influence in the region, and their dependence on the United States to prevent it, the Saudis could turn around and end up backing the accods. Conceivably, they could slow down or even stop their flow of funds to Jordan to pressure Hussein into the talks.

"If Saudi Arabia and the United States cut off the money," a former minister confided." "we are flat broke. The United States can apply financial, political and military pressure if it wants to get nasty."

To avoid such pressures, or the appearance of them, Hussein has declined Carter's invitation for a mid-October visit to Washington. But his vulnerability is obvious with a quick look at the budget. Of a total of some $900 million this year, about two fifths are provided by straight grants, with the United States, Saudi Arabia and Riyadh's allies in the Persian Gulf providing the lion's share.

Moreover, Jordan's backbone - the army - is almost totally dependent on the United States and Saudi Arabia. Washington this year is providing $55 million in grant funds. Saudi Arabia is paying for 14 Hawk missile batteries worth more than half a billion dollars, which constitute Jordan's only modern air defense system.

Some politically influential Jordanians, moreover, are tortured by what one man called "dormant, but very much alive" fears that the United States could decide the monarchy was expendable.

"The Americans might decide to solve the Palestinian homeland problem at monarchy's expense," one politician said.

Moreover, the lessons of 1948 are very much alive in Jordan, where Hussein's grandfather, Abdullah, was assassinated by a Palestinian for his part in accepting the Israelis and annexing the West Bank.

But to stay out, risk Saudi and American funds being cut off and end up relying on the likes of Libya is also an unattractive alternative. Hussein knows that accepting Libyan largesse would mean destabilization of another kind. Libya's Muammar Qaddafi has made clear that his price for renewed funding is allowing the guerrillas back into Jordan.

Nor does the prospect of increased Soviet influence in the Middle East please a man so openly pro-Western in mind and action as Hussein.

For all these reasons, Hussein appears in no hurry to make up his mind, despite suggestions Israel will be even more adamant about the West Bank if it concludes a separate peace with Egypt on the Sinai. Perhaps, he has intimated, that was all Israel - and the United States - ever wanted.

An Arab saying insists that "everything is born small and grows big except calamities." For Jordan, the except calamities." For Jordan, the best course may well prove to wait long enough - perhaps years - for the Arab world to digest a separate peace before deciding to join the game.