With a message of unity and a call to action, Oswaldo Payá Sardiñas spent a hectic day in Miami on Monday urging Cuban Americans to support his Varela Project, a grass-roots campaign -- unprecedented in Cuba -- that seeks a national referendum on civil liberties, the release of political prisoners and open elections.

He courted support from Miami's Cuban community, saying it will have an important role in his referendum and in the country's reconstruction after Fidel Castro.

''The role of the exile community is important in whatever changes happen in Cuba, primarily because they are an inseparable part of the Cuban people,'' said Payá, 50, a dissident who lives in Cuba but has spent several days in Miami.

Monday morning, Payá prayed privately with Bishop Agustín Román at La Ermita de la Caridad -- the Coconut Grove shrine to Cuba's patron saint. He had breakfast with a group of spiritual leaders, then was greeted with a standing ovation by 200 or so exiles at a ''conversatorium'' at the Father Félix Varela Center next to the church.

Security was tight as members of the Cuban Democratic Directorate, a Miami-based, human-rights organization with ties to the opposition in Cuba, spoke in walkie-talkies and shone purple lights on invisible ink to validate entries to the invitation-only events.

''It'd be very easy for the Castro government to try to take Oswaldo's life and then blame the exile community,'' said Janisset Rivero Gutierrez, the group's executive director.

More than a dozen uniformed Miami Police officers and another dozen or so plainclothes detectives monitored events.

Payá conceded that the Varela Project -- which takes advantage of a provision in Cuba's Communist constitution authorizing citizens to petition for legislative change -- was imperfect and not the only solution to Cuba's woes. Some critics say the referendum does not go far enough because it would allow Castro and the Communist Party to participate in a democracy.

SUCCESSFUL

The campaign has already been a success, Payá said, because it has made the Cuban people aware of an alternative and has chipped away at their fear -- despite the protests of critics who say the plebiscite won't be accepted by the Cuban government.

''Every day there are more people signing the Varela Project. They not only put their names on it, but their addresses and their identification numbers as well, and they are not afraid,'' he said. ``The Varela Project is a campaign that has its biggest strength in these heroic acts of citizens who have broken with fear.''

Payá said he welcomes disagreement ``because it breaks with the tradition -- pardon me, with the imposition -- that we Cubans have that we must define ourselves by one position, one politic, one ideology.''

CRITICS

He did not convince, however, at least a few of his most outspoken critics, who met privately with him Monday afternoon. Laura Vianello of Vigilia Mambisa said the meeting was cordial, but it appeared that nobody left with a change of heart.

''He has his viewpoint and we have ours,'' she said.

Still, she found the meeting beneficial: ``It puts things on the table. We spoke of our disillusionment as exiles and our thoughts.''

Dressed in a gray suit with a burgundy shirt and calling the members of the crowd his ''beloved brothers and sisters in the dissident movement,'' Payá was at turns humble and funny, affable and defiant.

''This is a moment of re-encounter -- the re-encounter of two parts of one people,'' he said. ``Let's speak freely. But let's speak responsibly. We live in two worlds but we are part of the same nation and we have one future together in the future of our homeland.''

But Payá mostly listened as others talked.

QUESTIONS

One man questioned how change could come about under Cuba's 1976 constitution, on which the Varela Project is based and which Cuban exiles deem illegitimate.

''The constitution denies many rights,'' Payá said, ''and in practice Cubans are denied many more rights that are in there.'' His initiative is simply a foundation on which to build, he said.

Emilio Izquierdo, a Bay of Pigs veteran and former political prisoner in Cuba, asked if he and others who had taken up arms against Castro could be part of a new Cuban democracy under Payá's plan, which denounces violence.

''It doesn't exclude any Cuban who has not directly intended to take someone's life,'' Payá said. ``Look, blood has divided the Cuban people and when I say this I talk with much affection and respect for those who have fought.''

The amnesty that Payá wants for political prisoners not convicted of violent crimes concerned Laida Carro, a Miami human-rights activist, who questioned relying on Castro's government to define a violent crime.

''You cannot take the word of a criminal government to be the judge of violent acts,'' said Carro, who advocates for several jailed dissidents.

Justice was a dominant theme as other attendees -- including the parents of one of four Brothers to the Rescue members shot down by Cuban government MiGs over the Florida Straits in 1996 -- asked what Payá's plan would do to people within Castro's regime that they consider criminals.

''We cannot face or confront any injustice because it would paralyze the process of change and that, too, would be an injustice,'' said Payá, who added that violent crimes have been committed on both sides of the Florida Straits.

THE EMBARGO

After a lunch with young, emerging Cuban American leaders, Payá met with The Herald's Editorial Board, where he said the embargo was a nonissue.

''Some people are trying to define whatever position you have based on your opinion on the embargo,'' he said. ``The embargo is not a factor in change in Cuba.''

Later Payá met privately with critics.

''It was important for me to meet this small group that doesn't support us, for me to have the opportunity to hear them because that will enrich us,'' Payá said. ``We are certain no project is perfect. Maybe we can clarify some points where the distance is not as great as we think.

``Even if they don't agree, they have every right to express their opinions, and their lack of support of the Varela Project in no way disqualifies them from participation.''

Angel de Fana, a former political prisoner, said, ``The question is not what I think about Oswaldo Payá personally, but what he stands for, which is the Varela Project that we oppose. I told him we didn't support it. He said that was our right.''

Later Monday evening, Payá attended a private reception at the home of Carlos Saladrigas, a prominent Cuban American businessman who said he had invited about 100 people, including critics.

SOCIAL GATHERING

''This is just a social respite to make him feel welcome, a brother in our community,'' Saladrigas said. ``It is not a political event.''

Among the guests at Saladrigas' Killian-area home were Miami Mayor Manny Diaz; Jose Basulto, leader of Brothers to the Rescue; and Carlos Alberto Montaner, an exile author-activist.

Payá also discussed the Varela Project on Maria Elvira Salazar's Confronta program on the AmericaTeve cable channel. Customers at a Hialeah La Carreta restaurant provided the opposing views, and viewers called in their own questions and comments.

Some viewers questioned Payá's legitimacy, observing that he has proposed radical changes but has not been jailed by the Cuban government.

Payá, who has been detained and harassed repeatedly and spent three years in his late teens at a labor camp for being a counterrevolutionary, said his wife and children suffer daily because of his activism. But he also said that he embarked on his movement when his wife was pregnant with their first child.

'I said, `My children are not going to leave Cuba. They are going to live freely in this country.' This brings consequences,'' he said, citing state security searches and surveillance of his family's movements. ``They have not had a normal life.''

Herald staff writer Tere Figueras contributed to this report.