In Latin America one of the common metaphors for relations between the United States and its 21 "sister republics" is a shark eating up all the little sardines. The present struggle over election of a new secretary general for the Organization of American States has proved that if enough of the sardines get together, they can at least frustrate the shark's appetite.

Jose A. Mora will step down next May after 13 years of service as secretary general of the OAS. So far the Central American and Carribean nations have managed to thwart the will of the hemisphere's great powers--the U.S., Brazil and Argentina--on the choice of a successor. This is an unprecedented development in the history of the organization, and it may set an important trend for the future.

There are three candidates for the post: Galo Plaza Lasso of Ecuador, supported by the big three, Marcos Falcon Briceno of Venezuela, and Eduardo Ritter Aislan of Panama. Ritter is the man causing all the trouble. There have been four ballots since November 17, and Ritter is ahead with 10 votes to Plaza's six and Falcon's five. It is a virtual deadlock--Ritter is two short of a majority--and the OAS has given up for the moment to let tempers cool. It will try again in January.

"For the first time they (the Central Americans) have found that by joining together they have a clout, that they can make an impact," Sol M. Linowitz, U.S. representative to the OAS, said. "They are holding fast to regional loyalty."

Linowitz feels that the Central American Common Market and its successes have contributed to the new-found political independence and solidarity of these countries. Highly placed American policy makers see this kind of political cooperation as a basically healthy development. They hope that the formation of a continental common market for all of Latin America will foster the same sort of cooperative spirit. Or that is what they say they hope.

What the United States is clearly unhappy about, however, is the purpose for which the Central American and Carribean nations have chosen to unite.

The U.S. government made it very plain whom it favored as the new secretary general of the OAS. Galo Plaza announced his candidacy for the post immediately as he emerged from Dean Rusks' office. They had had a long talk. Among Latin Americans, Plaza is considered very Americanized. He was raised in the States, educated here, and even played football for the University of Maryland. Since the assistant secretary general and the secretary for economic and social affairs of the OAS--the number two and three posts--traditionally go to Americans, many Latins are hesitant about giving their approval to a man whom they consider irreparably tainted by the colossus of the north.

Quite naturally, they fear he will be too "amenable" to Washington. But American policy makers question this point. Said one State Department official, "If malleability were the test, Plaza would be a far worse choice for us than the other two. We could probably control them far more easily." He pointed out that Plaza comes from the non-Communist Latin American nation which has given the United States the most trouble in the past year. Ecuador has demanded the withdrawal of our ambassador from Quito. We complied. And it was Ecuador's President Arismendi who delivered a stinging attack on U.S. economic imperialism in Latin America at the conference in Punta del Este last April. The speech was the only one which ruffled the placid self-congratulatory atmosphere pervading the meeting. And Plaza is a former president of Ecuador.

Political infighting over the secretary generalship has been ugly and high-pressured, often resorting to strong-arm political threats. Just last Thursday one of Ritter's partisans in the secretariat, Luis Raul Betances, a Dominican, was fired after another angry Dominican delegates reported that Raul promised to have him removed if he did not change his vote from Falcon to Ritter.

Had Raul's threats succeeded, Ritter's supporters would have been able to go into the last ballot only one vote short of a majority. They would have been in a strong position to pressure the rest of the member-states into line. But Raul failed, and the scandal has probably killed Ritter's chances.

Ballots are secret in this election, but Ritter's support almost surely came from Nicaragua, Costa Rica, Haiti, Honduras, Barbados, Trinidad and Tobago, Paraguay, Bolivia, Peru, and Panama. Marcos Robles, Panama's president, considers the election very important, and has reportedly been making phone calls to his colleagues all over the continent. Broad hints were dropped that if Ritter doesn't get the job, the United States might run into more trouble over the Canal Zone.

Part of the reason this high-pressure campaign has stymied turns on Ritter himself. Ritter reminds one of a Tammany Hall boss, a wheeling, dealing politician who knows the workings of the OAS inside out. But many feel he doesn't have the stature needed to put life and drive into an organization which today suffers badly from its own impotence and lack of imagination. Privately, most of his supporters are said to admit Ritter's failings, and two Central American republics, El Salvador and Guatemala, abandoned him somewhere during the four ballotings. It is these two votes that would have put him over the top.

But whatever the grubby details of the present fight over the secretary generalship, the fact remains that the Central American and Carribean nations for the first time have discovered strength in unity. For these countries, the fight for Ritter's candidacy has been primarily a nose-thumbing exercise at the United States, and at the big boys in South America who have always tended to look down on them because of the "special relationship" which they hold with the U.S. Also, South Americans consider South Americans to be less "pure" racially because of their large Indian population.

The decision on a new chief for the Organization of American States will probably be made in an atmosphere of sweet compromise next January. But the bitter battles over Ritter have been a testing ground for the small member-states of the Western Hemisphere. They may have welded themselves into a bloc which could achieve veto power over OAS policy, especially if more Carribean states join. Jamaica reportedly is moving to join the OAS. It will add one more to this new force in hemisphere politics.