AN AFRICAN guerrilla leader named Jonas Savimbi will arrive in Washington this week on a tour aimed at gaining U.S. support for his guerrilla war against the Soviet-backed regime in Angola. His goal, in simple terms, is to become America's "contra" in Africa.

Savimbi is a charismatic African politician. But his guerrilla movement cannot win and he does not deserve U.S. financial support or sympathy.

Savimbi's march on Washington this week highlights his astonishing transformation from Chinese-supported revolutionary to conservative-backed "freedom fighter." Barely six years ago he could not get an appointment even with the assistant secretary of state for African affairs, because Congress had passed a law forbidding American covert involvement with his forces in the Angolan civil war. But this week, Savimbi has an excellent chance for a private meeting with President Reagan in the Oval Office.

The Clark Amendment, which prevented his forces from gaining American aid, was repealed last year. So now he will be paraded through Congress as the American candidate for leadership not only of Angola, but perhaps all of southern Africa. He will be portrayed as the one man who can give Cuban troops a bloody nose and help restore American influence and prestige there. Tonight, Savimbi's new high profile will be evident to 40 million viewers in a scheduled appearance on CBS's "Sixty Minutes."

The trouble is that Savimbi simply isn't what his best American friends believe or wish he could be. "Savimbi is a master at telling people what they want to hear," says John Marcum, professor of political science at the University of California at Santa Cruz and one of the leading U.S. experts on Angola. "He has a quality of delivering a message in a way that pleases the ear of the listener."

Today that skill is being used to court American support, but in the past it has been employed to stir up sentiment against the United States.

Furthermore, Savimbi built much of his power base by overtly appealing to black-nationalist attitudes and antiwhite bias among some of Angola's tribal groups. His tactics are every bit as brutal and repressive as those of the government now in power in Angola -- if not more so.

He has proudly claimed to have attacked the installations of American and other Western companies. And he has lost most of his support from other African nations by collaborating with the white minority regime in South Africa.

Besides, UNITA is far from winning. In fact, U.S. aid to Savimbi now would prolong rather than shorten the Angolan war, and it would increase rather than end the Cuban presence in Angola.

The United States has no business taking a position on either side of this civil war. There is little in Angola's internal conflict that has anything to do with American national interests. And the risks are many. Funding Savimbi now would put the United States into a de facto military alliance with South Africa. That would violate the declared policy of the Reagan administration and would also alienate America's good friends elsewhere in Africa.

I have met Jonas Savimbi during his previous visits to the United States, and I have been greatly impressed with his political and rhetorical skills. He is a genuinely charismatic figure whose eyes seem alive with fire when he talks of the struggle in Angola. He speaks superb English (along with, it is said, Portuguese, French, and several other languages), and he is particularly adept at playing to the American fear of Fidel Castro, whose troops prop up Savimbi's enemy.

Other journalists who have visited him in the bush inside Angola -- it is easy to arrange trips from South Africa or Namibia on South African planes -- have been even more dazzled by Savimbi. They have heard him give dramatic, spellbinding orations to "party congresses" of his supporters, and they have been taken with his apparent willingness to stay at his fighters' side in their most difficult moments -- rather than spending much of his time in fancy restaurants in European capitals, as the leaders of other Third World nationalist movements have sometimes been known to do.

Nonetheless, it is one thing to recognize the mystique of Jonas Savimbi and quite another to commit American prestige -- and deficit financing -- to his cause. Those who would bankroll him as an American surrogate in southern Africa would do well to examine the recent history of Angola and Savimbi's own record.

Savimbi's involvement in the tangled politics and the violent struggle for control of Angola goes back to the early 1960s. That was more than 10 years before the country became independent, following a revolution in Lisbon, and was thrust into the unenviable position of a pawn in the East-West struggle. Although many students of African politics see Savimbi as an opportunist who adjusts his ideology to the needs of the moment, most still recognize him as a genuine Angolan nationalist -- a man whose record and credentials as an opponent of colonialism entitle him to some role in his country's future.

A member of the Ovimbundu tribe (which makes up about a third of Angola's population), Savimbi was born in the country's central highlands in 1934 to a family that one Protestant missionary described as being of "exceedingly humble, primitive, pagan background." Nonetheless, he graduated at the top of his high school class, and the missionaries, who saw great promise in him, sent him to Portugal for advanced studies.

Before long, however, he was being harassed by dictator Antonio Salazar's secret police for his political activities on behalf of Angolan independence, and so he fled to Switzerland in 1960, enrolling in the political science department at the University of Lausanne.

According to one State Department document that has frequently been quoted, Savimbi turned up at the American Embassy in Bern early in 1961, declared that he had been inspired by a speech by then-United Nations ambassador Adlai Stevenson in favor of self-determination for all peoples of the world, and introduced himself as "the future president of Angola."

Within months of making his ambitions known to U.S. diplomats, Savimbi had gone off to Leopoldville (now Kinshasa), the capital of the newly independent Belgian Congo (now Zaire), to join Holden Roberto, the leader of a generally pro-Western organization called the National Front for the Liberation of Angola (FNLA).

The FNLA was being aided and encouraged by the United States as an alternative to the Soviet-supported Popular Movement for the Liberation of Angola (MPLA). (It seemed unlikely to the superpowers that Portuguese colonial rule could last much longer on a continent where so many other countries were setting their possessions free, and in this period Washington and Moscow were characteristically choosing up sides among the new and future nations of Afica.)

But in 1964 the rivalry between Roberto and Savimbi came to a head, and Savimbi broke away from the FNLA. Two years later, he brought together his own cadres and formed a "third force," UNITA -- the National Union for the Total Independence of Angola. Savimbi found help from China, among others, and UNITA managed to play its own unpredictable part in the war against the Portuguese.

As independence approached in 1975, the military struggle in Angola turned into a tripartite civil war among the nationalist groups, and that doomed the prospect of open, fair elections. To the surprise of many outside observers, UNITA actually outlasted the FNLA, which, despite help from the U.S. Central Intelligence Agency, crumbled before the Soviet- and Cuban-aided MPLA.

Meanwhile, South Africa, concerned about the effects of the civil war on its neighboring territory of Namibia, had also intervened in Angola. Inevitably, the South Africans offered to help Savimbi, and he accepted.

The MPLA managed to establish a government in Angola's capital of Luanda late in 1975, and it has stayed in power since then with the support of a Cuban military and civilian contingent now estimated at between 25,000 and 35,000. But UNITA has also sustained its guerrilla struggle against the MPLA, with money and supplies from South Africa, for more than 10 years. Savimbi generally claims to control at least a third of the area of the vast country.

Last year, even as economic sanctions were being voted against South Africa, hardliners in both houses of Congress were successful in getting the law prohibiting American involvement in the Angolan civil war repealed. Savimbi's American backers believe that Angola is a place where the United States can stand up to the Soviet Union. It is on the strength of these conservative hopes -- that America can get back into the fray as a player in Angola -- that Savimbi is winging to Washington.

But before Savimbi is allowed to leave town triumphantly with a chunk of the American treasury, it would be a good idea to take a realistic look at the man who would be our newest African client.

Savimbi does not have the credible record as a moderate, democratic, pro- American figure that is so often cited on his behalf by his supporters in both parties here.

On the contrary, he built his reputation during the late 1960s and early 1970s as a fervid anti-capitalist, anti-American revolutionary. "No progressive action is possible with men who serve American interests . . . the notorious agents of imperialism," he said at the time of his break with Roberto. Among his leading supporters in the years that followed were Mao Tse-tung, Che Guevara, and Gamal Abdel Nasser.

During those same years, Savimbi drew a distinction between his own movement and the MPLA on the basis of their racial composition, denouncing the MPLA for its inclusion of, and alleged domination by, white radicals and mestizos (people of mixed race) who had accepted Portuguese citizenship.

Roughly one-tenth of the million people who live in the capital city of Luanda are white or mestizo, and the MPLA regime, whatever its other flaws, is multiracial in composition. "Given Savimbi's past statements on racial issues, (the whites and mestizos) all quiver at the thought of his coming to power," says Gerald J. Bender, professor of international relations at the University of Southern California and an advocate of American diplomatic recognition of the Angolan government.

Although Savimbi has been wise enough to alter his pro-Marxist, antiwhite rhetoric when it is expedient to do so, the UNITA slogan remains "Socialism, Negritude, Democracy, and Nonalignment." No one really knows what his policies would be if he were to come to power. As The Washington Post's Leon Dash reported in 1977 after spending seven months with UNITA forces in the bush, "Savimbi is an enigma, a man on whom many labels can stick -- brilliant, charismatic, affable, unyielding, forgiving, temporizing, Machiavellian, opportunistic, lying, nationalistic, Marxist, Maoist, pro-Western and socialist."

Savimbi is miscast as a "freedom fighter" defending Western ideals against a harsh Marxist regime.

UNITA has in fact been criticized for its brutal tactics in the Angolan countryside. In classic guerrilla fashion, its acknowledged goals are to grind the Angolan economy to a halt, prevent development, and destroy agriculture -- all to stir up discontent with the government.

Among the foreigners taken prisoner during UNITA attacks in recent years have been many missionaries and church workers. Just last month, in an incident reported by the Brazilian Embassy in Angola and three religious organizations, five Baptist church workers were killed, three wounded and two women carried off by Savimbi's men.

And one of the sharpest ironies of the situation in Angola is that the MPLA government finds that it needs the Cubans to help protect Gulf Oil rigs and storage tanks from threats by the South Africans and the allegedly pro-American UNITA forces.

Savimbi is not the popular pan-African politician that he often claims to be.

It is true that in the period just after independence the Organization of African Unity (OAU) was sharply divided on the issue of whether to recognize the MPLA or some FNLA/UNITA coalition as the legitimate government in Angola. But as soon as the nature of Savimbi's connections with South Africa became known, he lost much of his support elsewhere on the continent.

Savimbi travels to and from Angola primarily through South Africa and South-African-controlled Namibia; his headquarters in Jamba are only 18 miles from the Namibian border. The government in Pretoria is proud of its connection with UNITA, claiming that it proves South Africa's ability to work with the "right" kind of black African leader. In fact, Savimbi was an honored guest at the inauguration of State President P. W. Botha in 1984. To this day, most African governments depict Savimbi as a South African puppet.

Further American assistance to Savimbi, overt or covert, will not lead to withdrawal of the Cuban forces in Angola.

On the contrary, every South African intervention on UNITA's side in the past has caused an increase in the number of Cubans. There is no reason to think that American aid would produce a different result. In recent meetings, Angolan President Jose Eduardo dos Santos has reportedly warned Chester A. Crocker, assistant secretary of state for African affairs, of that fact, and he has frankly asked the Reagan administration not to push Angola into a greater dependence on the Soviet Union.

The Angolan leadership claims it would like to send the Cubans home gradually and take a more truly non-aligned posture in foreign policy. But the regime insists that this is impossible so long as UNITA continues its military efforts and South Africa continues to invade Angolan territory at will.

Savimbi is not on the verge of winning the power struggle in Angola, and few outside observers, including the American intelligence community, believe he has any chance of doing so at any time in the near future.

Then-CIA director William Colby estimated in the mid-1970s that it would take some $100 million in outside aid for the "pro-Western" forces to prevail in Angola, and the United States put in about $14 million before the Clark amendment took effect.

Today, U.S. officials estimate that if the MPLA were strengthened and substantially greater Soviet-funded Cuban assistance were offered, even $200 or $300 million -- far more than anyone is suggesting the United States might be able to provide -- would probably not do the job. With or without an infusion of U.S. funds, the Angolan civil war is locked in a stalemate.

Jonas Savimbi's visit to Washington, then, has little to do with the real prospects for peace in southern Africa, and a great deal to do with American politics.

Two significant forces are arrayed on Savimbi's side: liberal Democrats who believe they have to demonstrate their ability to support a tough, anti-Soviet foreign policy; and conservative Republicans who, having voted last summer for economic sanctions against South Africa, have been under pressure to take some other persuasive, anti-communist steps in the region.

An example of the former is 85-year-old Rep. Claude Pepper (D-Fla.), who has an increasing number of anti-Castro Cuban exiles in his district demanding he take a tougher stand.

An example of the later is 50-year-old Rep. Jack Kemp, (R-N.Y.), who was warned by some of his bedrock conservative supporters that his vote for South African sanctions could cost him the GOP presidential nomination in 1988.

Pepper and Kemp make an interesting coalition, but they are crafting bad foreign policy. To be wary of some of what the MPLA has done and to wish for an end to the Cuban presence in southern Africa does not require support for a harsh and unprincipled guerrilla leader about whom the American government and people actually know very little. To be skeptical and cautious with Savimbi does not imply endorsement of the regime in Luanda.

It is fine to treat Savimbi to some good, old-fashioned, all-American hospitality; we have done as much for many unsavory types from all over the world in recent years. But if we offer him new aid -- either "overt" or "covert," however it is packaged -- the people of Africa, as usual, will be the biggest losers of all.