Despite the revolutionary euphoria of the past month, the first signs of organized opposition to Nicaragua's new government are coming from the extreme left and not, as widely anticipated, from conservative businessmen.

At the same time, the government's first act of political impatience has been to expel some 60 Latin American Trotskyists whom it charged with being "counterrevolutionaries" and "creating problems for the Sandinista revolution."

Although the government is anxious not to disappoint popular expectations of change, it seems determined to resist extremist pressure for sudden, radical measures that could frighten both the domestic and foreign private sectors and retard economic reconstruction.

The radical left, mainly Maoists and Trotskyists, on the other hand, has been trying to force the government's hand through such provocative actions as takeovers of private firms, instigating workers to seize control of factories and urging "popular militia" not to surrender its weapons to the new Sandinista army. In most cases the government has quickly intervened to prevent these actions.

Perhaps most irritating to the Sandinista leaders is the fact that many of the most militant leftists, notably the Trotskyists, were not directly involved in the fighting to overthrow the Somoza government but rather rushed here from abroad to reap the harvest sown by the Sandinistas.

The anger of the leadership here came to a head last Wednesday when members of the Trotskyist Simon Bolivar International Brigade organized a worker protest outside the Sandinista military headquarters in Managua.

More than 3,000 factory workers shouted demands for lost salaries during the war and some carried banners saying, "The revolution is in the hands of the bourgeoisie" and "power to the proletariat." About 100 Popular Militia members following them claimed to be the "true vanguard of the people" and shouted for weapons.

But within 24 hours the government had put 60 of the "foreign provocateurs" on a plane to Panama and warned it would not tolerate pressure from either extreme left or right.

"Those people who during the struggle said we were not revolutionaries, called us adventurers or bouregeois, are not now coming to teach us any lessons," Daniel Ortega, a member of the junta and one of the main Sandinista ideologues, said in a speech.

This first test case of Sandinista reaction to dissent from outside Sandinista ranks also demonstrates that it is possible for the more radical groups to seize on elements of discontent.

Aware of the immense popular support for the Sandinista guerrillas who led and won the war, the Maoists and Trotskyists used Sandinista slogans and flags while instigating workers and peasants.

But the Sandinistas are aware that resentment against the frequent release of imprisoned members of Somoza's National Guard, the food shortages in some areas and particularly nationwide unemployment, are ingredients making for instability that could threaten their strategy of making far-reaching social and economic reforms with the broadcast possible political base.

In recent days, leaders of the Sandinista command and junta members have said privately they fear they may be caught in a vicious circle; they require fast massive foreign assistance to ensure that moderation prevails, yet Western governments appear to be withholding funds until they can be sure they are not financing "a new Cuba."

"We are living an unbelievable emergency. If the shortage of money, work and food does not decrease, we may have to take emergency measures, with tight state controls over the production apparatus or food rationing, which we don't want," was a typical comment of one Cabinet member. He pointed out that few people in the country, including government and army employees, had been paid since the war.

"This revolution which cannot be stopped now, would have to be carried out by the state only, without private enterprise," he said.

There is also high-level apprehension about "a hostile attitude" of some Western, particularly American, reporters who, junta member Moises Hassan said, "Do not look at the content, the social project of this revolution but are only communist-hunting in the worst form of McCarthyism."

Some U.S. diplomats here agree that several reports in the U.S. media have been "irresponsible," or "distorting the truth." This applied, they say, to cliches about "the new Cuba" and "rising anti-Americanism."

By Latin American standards, in fact, there has been very little anti-Americanism in Nicaragua and in the last two weeks there has been less anti-U.S. rhetoric or feeling displayed than on a normal day in Mexico or Panama.

One U.S. official said, "We are mesmerized by the Cuba idea. But I've been in many countries with so-called better relations with more hostility for much less reason than Nicaragua."

In an interview with foreign correspondents, U.S. Ambassador Lawrence Pezzulo described his relations with the Sandinista government as "as cordial and easy as I've ever witnessed with any government. We converse easily, meet easily and have a lot of mutual business going on."