Fighting mounting political and labor turmoil, President Violeta Barrios de Chamorro is promising to replace the longtime Sandinista military chief soon and open talks to disarm Contra rebels. The leader of the new U.S.-backed government also said Monday she is disbanding the secret police, which the leftist Sandinistas had controlled. Mrs. Chamorro, speaking at her first news conference since she took office last week, also gave an idea of the economic difficulties she faces. She said the Sandinistas had left just $3 million in the treasury and an $11 billion foreign debt. ``That is why it is urgent that we apply severe measures that will allow us in the short term to stabilize the currency and prices, to guarantee investment and the productive effort now that this year's agricultural cycle is starting,'' she said. Last week, Mrs. Chamorro devalued Nicaragua's cordoba by about half. The devaluation sharply increased prices, causing more hardship in an already poor country. Mrs. Chamorro on Wednesday succeeded Daniel Ortega after a decade of Sandinista rule and nine years of war with U.S.-backed Contras rebels. On Monday, she said she would pursue reform as soon as possible and appealed for support from both friends and foes. Her shaky new government faced new challenges today, with two labor groups planning separate protests to mark International Labor Day. A Sandinista union has organized a protest to back demands for 100 percent pay raises for all workers and the disbanding of Contra rebels. Four anti-Sandinista unions were to rally to demand the removal of Gen. Humberto Ortega as the armed forces chief. At her news conference Monday, the president promised that Ortega, the brother of the former president, will remain only temporarily as chief of the armed forces. She also said she would hold talks Wednesday with Contra military chief Israel Galeano to ask him to disarm his forces. Mrs. Chamorro's decision to serve as her own defense minister and keep Ortega as commander split her own 14-party United National Opposition, which she led to a landslide victory in elections Feb. 25. The Contras promised to surrender their weapons and disband by June 10, then balked after Mrs. Chamorro announced that Gen. Ortega would remain military chief. They say they want an end to Sandinista control of the military and police. At her news conference, Mrs. Chamorro said she understood how her supporters ``would like a drastic and immediate change'' in the armed forces. But she added: ``We need to do things well, even if it means resuming temporary sacrifices to guarantee the tranquility and stability of the country.'' She repeated that she had told Gen. Ortega several times his job was temporary, and she explained she kept him on ``to ensure the unity and discipline of the army'' while the Contras disarm. She announced that the powerful secret police force, which was run by the Sandinista Interior Ministry, is being disbanded. But she did not go into details. She also said she was ending the use of exit visas, which the Sandinistas required that both Nicaraguans and foreigners obtain to leave the country. Mrs. Chamorro further appealed to her vice president, Virgilio Godoy, to remain loyal. He is engaged in a bitter power struggle with some of her close advisers. On Monday, he was on an unexplained trip out of the country. ``I trust that the vice president ... will accompany and support me with the total loyalty in the making of the great decisions and in the fulfillment of the complex tasks with which the people of Nicaragua have entrusted us,'' she said.