The hazards invited by the Carter administration's attempts to compete with Moscow for the affection of Africa's "progressive" nations became clear in the reaction of Julius Nyereres Tanzania to Washington's new policy. President Nyerere's position can be authoritatively described as follows: President Carter's tough stand against white-ruled Rhodesia and South Africa "is a far cry from the Kissinger policy" and warmly appreciated. But U.S. "non-lethal" aid the Zaire during last spring's Communist-backed invasion was a "hangover" from the bad old days, greatly to be deplored. Futhermore, it is noted that the "armed struggle" against Rhodesia is still paid for by Moscow, not Washington.

The message is chilling but clear. To achieve the Soviet Union's status in "progressive" Africa, the United States must abandon its "conservative" friends - particularly President Mobuto of Zaire - and support a military assault of white-ruled southern Africa. In short, Nyerere wants Washington to duplicate the Kremlin's policy, which was specifically tailored for maximum Soviet influence on the continent.

This does not mean Nyerere is a Soviet agent but it does reflect basic incompatibility between U.S. interests in Africa and the "progressive" bloc. Whereas Nyerere is referred to by AMbassador Andrew Young as "my mentor" and is the favorite of touring congressional liberals, his rigid policies, both internal and enternal, run much closer to traditional Soviet than American models.

This hard reality is partly obscured because Nyerere, who earned his master's degree at Edinburgh, can test the intellectual mettle of even Henry Kissinger. U.S. officials enjoy the challenge of dealing with Nyerere and are reassured when he passes slighting remarks, fairly common among leftist African leaders, about the Russians.

But Nyerere's record speaks louder than words. He supported the Soviet-backed Cuban intervention in Angola from the start. He intervened with Tanzania troops when Mozambique's Marxist government was threatened by armed resistance. He was blatantly sympathetic to armed rebellion - traced to Angolan, Cuban and Soviet sources - against Zaire.

As the most prestigious of the "frontline" presidents, Nyerere has grown closer to the Soviet Union as principal supplier and financier of guerrilla warfare against white Rhodesia, no matter what he might say about the Russians in private. His government perceives no ulterior Kremlin motive in its bountiful financing of the Rhodesian war "The Soviets would just like to have a government in Zimbabwe [Rhodesia] that does not hate them," Sammie Mdee, an intimate Nyerere adviser, told us.

The government-owned Daily News recently called for a Zimbabwe government that is not merely black but also Socialist and revoluntionary - a view, we were assured by high-level sources, that reflects Nyerere's own. Thus, the Tanzania government is neither interested in preserving Rhodesia's highly developed private-enterprise economy nor worried about Soviet influence in Zimbabwe. That fits this reality Julius Nyerere may be one of Africa's most respected leaders, but there is no more doctrinaire Socialist on the continent. His regime looks with contempt across the border into Kenya, where an open door to private investment and tourism produces a buoyant economy in sharp contrast to Tanzania's prolonged stagnation (alleviated recently by high coffee prices).

Kenya, Zaire and, most of all, the United States are viewed here as exploiters of the common man. Indeed, the Americans are seen as ideological adversaires. If there is a model to which Tanzania socialism aspires, it is the faceless, dehumanized communism of China.

Western political models are no more popular here than are Western economic models. Nyerere runs a typically African one-man, one-party show, but 3,000 political prisoners (exceeding South Africa's total) in a country with no overt insurgency is excessive even by African standards.

Such repression, sluggish economic development and the physical deterioration of Dar Es Salaam are supposed to be compensated for by egalitarianism and freedom from the high-level corruption permeating Kenya and Zaire. But diplomats, businessmen and ordinary Tanzanians told us of petty corruption at middle and lower levels that impedes commerce and torments the average citizen.

There are then elements of hypocrisy when the new moralism in Washington, assailing repression in South Africa and complaining about corruption in Zaire, finds no quarrel with Tanzania. An answer is that the political and economic unpleasantness here is nobody's business but the Tanzanians', and the Carter administration should be commended for restraint in its moralizing at least here.

That still leaves unresolved the question whether Nyerere's standard is suitable for U.S. policy to set its African course by Nyerere's high esteem in Washington, reflected by his coming state vist, suggest Andrew Young is not the only U.S. official who thinks so.