MANAGUA -- Sandinista party leader Daniel Ortega's stepdaughter leveled a politically explosive charge of sexual abuse at him Tuesday, accusing him of molesting her as a child.

In a letter faxed to news media, Zoilamerica Narvaez, 30, said Ortega -- who was president of Nicaragua for more than a decade -- abused her ``in a repeated manner, for many years,'' beginning when she was 11.

``To overcome the effects of this prolonged aggression, with all the harassment, threats, pressures and blackmail that accompanied it, has not been easy,'' Narvaez said in her letter.

Ortega, at a brief press conference where no questions were permitted, said only that his stepdaughter's charge ``causes us pain and sadness.'' But his wife, Rosario Murillo, called it ``a total falsehood.''

In a country where sexual gossip about political personalities rarely finds its way into the news media, the accusation resounded like a tropical thunderclap.

Conspiracy theories

And it raised immediate suspicions of a political conspiracy. The Sandinista party, battered by eight years of electoral defeats, has scheduled a convention in May to plot its future. One of the major issues is expected to be Ortega's leadership.

To further fuel the conspiracy theories, Narvaez herself is a figure of some importance within the Sandinista party and is vice president of a committee charged with reforming the party. The committee has clashed on several recent occasions with party leaders closely allied to Ortega.

But Ortega himself Tuesday said that any suggestion that the abuse charges were part of an attempted political coup against him ``causes us anger.'' Narvaez said she hoped there would be no political fallout but couldn't be blamed if there was.

``I have the right to defend my identity,'' she said, ``even if this disturbs positions of power.''

Rumors of a sexual liaison between Ortega and his stepdaughter have circulated through Managua for nearly a decade. And Narvaez acknowledged Tuesday that she had told the story to ``many people'' over the years, though never publicly.

``Many people know, many people are not surprised,'' she said. ``But I will not name them.'' She ignored questions about whether she confided in her mother, but did say: ``She knows I love her.''
Dropping Ortega name

Though Ortega and Murillo have never formally married, they have lived together for nearly two decades and have eight children. Narvaez, however, is one of two children that resulted from Murillo's teenage marriage to a man long dead.

Narvaez, executive director of a think tank here, has published many journal articles and even a book under the name Zoilamerica Ortega. But in her letter, she said she was dropping it because ``for ethical reasons, I can't identify with it.''

Ortega, she said, ``in spite of his position as the father in my family, abused his power, planted fears and uncertainties in me from the time I was a little girl, and affected the emotional development of my childhood and adolescence.''

While Narvaez, who is married and has two children, was composed and even smiled occasionally during two brief encounters with reporters Tuesday, Ortega and his wife both appeared haggard and on the verge of tears during theirs.

As their eight children and several senior Sandinista officials stood behind him on a stage at party headquarters, Ortega spoke only a few sentences before turning the microphone over to Murillo.

Replying with `love'

``We are shocked, we are wounded, we are hurt,'' Murillo said, but added: ``We have no rancor, we do not house resentment. . . . We want to reply only with love.''

Calling Ortega ``a man of irreproachable moral quality,'' Murillo wondered aloud why her daughter ``would want people to lose respect for a man who has given himself to the people with personal consideration. . . . What motives can she have to want to destroy him as symbol of values and commitment?''

Murillo, however, said that neither she nor Ortega would be answering those questions. ``This is a family matter,'' she said, not for public discussion.

Child molestation is a crime that can be prosecuted without a signed complaint, but authorities said that because Ortega is a member of Congress, he has parliamentary immunity and can't be charged with anything.