Amman, Jordan — Jordan's King Hussein - the traditionally pro-Western monarch who recently launched a fierce public attack on United States Mideast policy - would, oddly enough, vote to reelect Ronald Reagan this November if he could.
This, at least, is the message conveyed in private remarks by Jordanian sources and senior foreign diplomats here.
King Hussein, himself, said in a London radio interview Sunday that, on a personal level, ''I respect and admire'' Mr. Reagan.
But the King - whom the Americans have long viewed as crucial to any widened Arab-Israeli peace negotiations - seems to have more fundamental reasons for hoping Mr. Reagan holds sway at the polls this November.
Western and Jordanian sources here suggest two especially important factors:
* The King feels any revived US role in brokering Mideast peace must involve a forceful show of US ''evenhandedness,'' specifically a move to pressure Israel for concessions to help bring Jordan and other Arab ''moderates'' into a negotiating process.
''The King says in private that the last US president capable of fulfilling such a role was Eisenhower, whom he deeply admires,'' remarks one senior European diplomat. It was Eisenhower who in effect forced Israeli, British, and French forces to pull an invasion force out of Egypt in 1956. ''Hussein feels Reagan has similar strength of character and commitment.''
* The King is reportedly convinced that a string of one-term US presidential administrations has ruled out the kind of sustained, continuous US negotiating effort central to any real progress toward Arab-Israeli peace. The King feels, says one Amman source familiar with his thinking, that things have reached a point where a US president spends some two years familiarizing himself with the Mideast and gearing up for action, has a mere year or so to act, and then has to run for reelection.
And elections - not only the American ones, but Israeli balloting scheduled for this July - are much on the mind of the Jordanian monarch as he marks his 32 nd year on the throne.
As for Israel, the King implies hope the opposition Labor Party alliance will unseat seven years of right-wing government. ''The Labor Party was obviously in power earlier on,'' he said at a news conference capping a visit here by the British royal family last month. ''We were not able to get very far'' toward negotiated peace - presumably a reference to a long series of nominally ''secret'' contacts between Hussein and Israeli Labor governments in the past.
''But I am very interested in the phenomena that we see, that Labor appears to be more responsible in terms of its announced position so far, and for a party in opposition to adopt such an attitude is very interesting.
''And if Labor as a result comes to power, then maybe there is a change that is a healthy one in Israel, itself. We will have to wait and see.''
Yet Hussein's main electoral interest focuses on the US. Amid an ever widening Israeli civilian presence on the West Bank of the Jordan River - which Israel captured from the King in the 1967 Mideast war - Hussein seems concerned any internal Israeli political change risks coming too slowly to salvage hopes for a negotiated peace.
The King is said by informed Amman sources to feel that energetic US intervention in the Arab-Israeli stalemate - including pressure on Israel to freeze civilian settlement in the West Bank - is imperative to revive negotiation prospects ''before it is too late.''
One Jordanian official stresses, ''the King did not intend his recent comment as an attack on Reagan. But he is genuinely disillusioned with the thrust of American policy.''
The King's public blast at US policy came in a New York Times interview two months ago, amid his rancor at Reagan administration difficulties in pushing a proposed arms sale to Jordan through Congress.
''Israel is on our land,'' he was quoted as saying.
''It is there by virtue of American military assistance and economic aid that translates into aid for Israeli settlements.
''Israel is there by virtue of American moral and political support to the point where the United States is succumbing to Israeli dictates.
''This being the case, there is no way by which anyone should imagine it would be possible for Arabs to sit and talk with Israel as long as things are as they are. . . . You obviously have made your choice, and your choice is Israel. Therefore, there is no hope of achieving anything.''
If the King was angered partly by the arms-sale logjam, his comments could not have done more to harm his cause. The Reagan administration promptly withdrew the request for congressional approval.
Hussein - who several years ago bought some Soviet missiles after a similar US rebuff - demonstratively began seeking an alternative to the latest nixed sale, in China among other places.
But in the past two months, Hussein has in effect rolled back on his public blasting of the US. He says his principal aim was to jolt the American political arena into serious debate of Mideast policy.
One possible explanation for the roll-back came at the end of the King's April news conference. Asked whether anyone other than the US or the USSR was in a realistic position to mediate Mideast peace, he replied:
''No, especially the USA. . . .''