Walter Guevara Arze, the deposed constitutional president, made a dramatic appearance tonight before the Congress that originally elected him and declared that "the Bolivian people are fighting for their liberty, for the right to govern themselves."

Guevara, who has been in hiding since the military coup last week, told the Congress, "I have not resigned nor will I resign the mandate conferred on me by resolution of the Congress last Aug. 6. I am not fighting to regain the presidency for myself but for the people who have sacrificed so much."

Guevara's appearance tonight added another twist to the already confused and complicated political situation a week after Guevara was overthrown by Col. Alberto Natusch Busch.

By reasserting that he is still president and warning the Congress that it risks political suicide if it enters into an accord with Natusch's unpopular and isolate military regime, Guevara reinforced his role as the leading symbol of democracy here.

Although Bolivia was returning to normal after Natusch lifted martial law and press censorship last night and promised to free political prisoners, there is still no agreement on how to resolve the political crisis.

The appearance of Guevara, Bolivia's first civilian president in 10 years, was received as an act of both personal and political courage. Police and military authorities have searched for hime since he managed to escape his residence during the coup last Thursday and go into hiding.

Guevara, who arrived at the Congress in sports clothes and a wig, was cheered as he entered the building by those who recognized him and nearly mobbed him as he left after his speech.

He clearly has become a symbol of resistance and several members of Congress said after his speech that it now appears that the elected Congress once again will ratify Guevara as the constitutional and legal president.

For the past several days, mediators between the military government and the Congress have been trying to reach an agreement whereby a member of the Congress, probably its president, Lidia Guiler, would become co-president with Natusch.

But that possibility, which had already lost support in the Congress because the largest labor union federation refused to nominate a third representative to the proposed junta, almost certainly ended with Guevara's speech, several members of Congress said.

After recounting how he had tried to dissuade the military from going ahead with the coup -- which led to passive and armed civilian resistance that has resulted in at least 70 dead and hundreds wounded -- Guevara called on the military to recognize its mistake.

"Bolivia is now confronted with the alternatives of converting itself into a country occupied by the military or defending its liberty and right of self-government," Guevara told the Congress.

"The armed forces, for their part, are confronted with the dilemma of shooting their brothers or returning to their barracks and allowing the people to continue with the democratic progress that so many have sacrificed themselves for and which has cost so much."

During the 40-minute drive from the house where he spent the afternoon to the Congress, in the center of La Paz, Guevara nervously made small talk with those who accompanied him.

Before leaving the safe house, Guevara rehearsed his speech, settled on the safest route to the Congress and planned his exit -- through the congressional kitchen.

One the way to the presidential mamsion, Guevara told of his plan to sponsor a contest for Bolivian artists to fill the house with paintings and another plan for his wife to give a televised tour of the mansion "like Jacqueline Kennedy."

But, he said, there had been no time for that.