A growing political polarization has come into the open in Nicaragua, eight months after the Sandinista movement overthrew dictator Anastasio Somoza with the backing of a huge majority of Nicaraguans of all political tendencies.

As the new rulers struggle with the serious economic problems left by the war and the corrupt Somoza government, those Nicaraguans who are not firmly committed to the Sandinistas' plans to remake Nicaraguan society have begun to accuse the government of restricting political freedoms and to demand elections.

The leaders of several opposition parties as well as some parties allied with the ruling Sandinista National Liberation Front have reported large increases in their membership.

These parties saw the past weekend's visit of Venezuelan President Luis Herrera Campins as a good opportunity to show their strength and express their demands while demonstrating that a wide spectrum of political opinions can be expressed in revolutionary Nicaragua.

Herrera, a Christian Democrat, comes from a country with several political parties.

But their attempt backfired.

The plan had been to station throngs of supporters of the Democratic Conservative Party and the Nicaraguan Democratic Movement (MDN), with their distinctive party banners, in the Plaza of the Revolution where Herrera was to speak so that, along with the Sandinista banners, a mixture of political views would be displayed.

The Nicaraguan Democratic Movement stationed its members in front of the reviewing stand early in the morning. But shortly before Herrera and members of Nicaragua's junta arrived, a truck carrying members of the Sandinista Labor Federation pushed through the Democratic Movement supporters. Their flags were torn down, some were burned and signs were torn up.

When Democratic Movement leader Alfonso Robelo, a member of the junta, arrived, the plaza was a sea of red-and-black Sandinista flags.

"I knew we had more than 50 flags," he said, "but when I looked, all I could see was one or two MDN flags in the back of the crowd."

Venezuela is particularly important to Nicaragua both because it has agreed to provide a large amount of badly needed aid and because it was involved in international talks before the ouster of Somoza that yielded promises by the Sandinistas to create a democratic government here.

Herrera is seen here as a representative of those countries in the hemisphere that do not want the Nicaraguan revolution to become like the Cuban one.

In his speeches, Herrera was careful to avoid any appearance of telling the Nicaraguans what to do. But at each public appearance in his busy two-day schedule he mentioned the importance of democracy and "political pluralism."

In a series of meetings with representatives of a Christian Democratic union federation and three opposition parties, Herrera was informed of restrictions on their activities.

A leader of the labor federation -- the Federation of Nicaraguan Workers -- said his office has been shot at, leaders had been detained and Sandinista commanders had tried to break up union meetings.

Leaders of all the opposition parties complained that they have no access to the Sandinista-run television network and have difficulty getting their opinions broadcast on radio.

Robelo's party, although it is part of the Sandinista-sponsored coalition, has expressed some of the same concerns the opposition parties have. In a well-attended rally here two weeks ago, Robelo told a wildly enthusiastic crowd his party believes in "ideological pluralism, effective democracy . . . electroal freedom, the free interchange and publication of ideas and freedom to organize."

The Sandinista Front has taken a hard line in response to the increasing political activity. It has said that instead of the "bourgeois freedom" of traditional democracies, the revolution is providing a new kind of freedom for Nicaraguan workers and peasants to organize and make their voices heard. It has said opposition parties represent only the interests of the bourgeoisie, which has always exploited the poor.

As if in response to demands for elections, the Sandinista Labor Federation put up huge billboards in the plaza for the rally to welcome Herrera, saying: "The people have already voted . . . Sandinista Front for the liberation of the people. People's power is Sandinista power."

Some observers wonder how much effect critics of the Sandinista Front can have, since the front controls the government, the armed forces and large grass-roots organizations of workers, peasants and others.

The political parties apparently hope that they can capitalize on the discontent of those who are unhappy with certain government actions and rely on international help if the government moves against them.

After Robelo's widely publicized rally, the nine-member Sandinista National Directorate called on him to "reflect" on his "errors."

Since he is one of two non-Sandinista members of the five-person junta, any move to get rid of him would be interpreted abroad as a retreat from the pluralistic society the Sandinistas promised when they took power.