Salvadoran President Alfredo Cristiani, struggling to persuade a doubtful Congress that his government deserves continued U.S. military support, said yesterday that he is prepared to accept a major reduction in military aid as long as it is tied to a cease-fire agreement by anti-government rebels.

In addition, Cristiani said he would name a "blue ribbon panel" of three prominent U.S. judges to advise his government on how to prosecute Salvadoran military personnel allegedly involved in the killing last November of six Jesuit priests.

Cristiani's inability to try the soldiers nine months after their arrest, coupled with allegations that senior officers have destroyed evidence in the case, sparked congressional efforts to cut aid.

A bill passed by the House last spring would withhold half the $85 million in military aid requested for El Salvador by the Bush administration, and award it only if the leftist rebels, known by the initials FMLN, engaged in major offensive operations or declined to participate in peace negotiations. All the aid would be terminated if the Salvadoran government ended talks or failed to conduct a full investigation of the Jesuit killings.

A similar bill introduced in the Senate by Christopher J. Dodd (D-Conn.) and Patrick J. Leahy (D-Vt.) is likely to be approved by the Senate Appropriations Committee in the next few weeks, according to its supporters.

In an interview, Cristiani effectively conceded the inevitability of some cut in the aid request. "The percentage {withheld} is not a problem," he said, but he insisted that any withholding be conditioned on rebel agreement to a full cease-fire. The FMLN has said it could not agree to a formal cease-fire, which would oblige it to move its forces out of urban areas, until there are "irreversible" changes in the military high command.

Dodd, in an interview, said he doubted Cristiani would prevail in conditioning aid approval. "If the vote were held today, we think we can produce 55 votes. People up here are tired" of the civil war, he said. Cristiani's three-judge panel idea is "not going to fly," Dodd said, because "it's an admission" that the Salvadoran system cannot bring the killers to justice.

"All that he is saying," Dodd said, "is once again 'give me the money, trust me guys.' The House flatly won't accept that and neither will the Senate."

Cristiani did not specify which U.S. judges he had invited to serve on the panel. He said two had tentatively accepted, and one had not decided.

Senate aides on both sides of the issue said it was not clear that proponents of the aid cut could prevail against a concerted administration effort to come up with a substitute bill. But the administration, distracted by the Persian Gulf crisis, has yet to mount such an effort.

Unlike prior aid fights, in this round events outside Cristiani's control have tilted the domestic political landscape sharply against him, all but erasing arguments that won the day for military aid in the past.

The cold war arguments that used to keep wavering congressmen in line -- and secured about $4.5 billion in aid to El Salvador in the last decade -- have been substantially undermined by the Soviet Union's retreat from the region, by the Sandinista electoral defeat in Nicaragua and by the perceived weakness of President Fidel Castro's government in Havana.

At the same time, mounting U.S. domestic budget troubles and the possibility of war with Iraq have pushed El Salvador onto a distant back burner for many members of Congress.

Responding earlier to concern about the Jesuit killings, the administration said it would agree to withhold 15 percent of the total $85 million if the government did not fully investigate the killings, comply with a cease-fire or adequately reform the military and judicial systems. Another 15 percent would be withheld if the FMLN was complying with a cease-fire.

But the administration insists 50 percent is too deep a cut, and argues, with Cristiani, that the Dodd-Leahy bill would encourage the FMLN to harden its position in the negotiations and to stall or engage in another offensive.

The congressional debate also is likely to be influenced by United Nations-sponsored peace talks that began between the Cristiani government and the FMLN last spring. The talks are now deadlocked over the question of how much change in the military is needed before a cease-fire can be implemented.

The upcoming Senate debate may focus on what signal the United States wants to send to the opposing sides to break their negotiating impasse. Supporters of the 50 percent cut say it sends the appropriate message of disapproval to the Salvadoran government. At the same time, it would give the administration leverage over the FMLN not to attack, because such an attack would result in full military aid being restored.

The administration wants "to send two signals," said Bernard W. Aronson, assistant secretary of state for Latin America. "We want to say yet again that the Jesuit case is and continues to be a turning point, and we will not forget. Those atrocities must be punished. Some portion of the aid can be contingent. But we also want to send a message to the FMLN {not to} wait for the U.S. to bail you out. Don't stall on a cease-fire."

Other State Department officials agreed with Sen. Richard G. Lugar (R-Ind.) who said that if the conditions adopted for obtaining aid were too stringent, "we can write ourselves out of the scenario" and leave the field to radicals on both sides in El Salvador who want "to settle their problems in the old-fashioned way," through an all-out military confrontation.