The plotting began almost three weeks ago when two members of Bolivia's house of deputies, Guilermo Bedregal Gutierez and Jose Fellman Velarde, approached Col. Albert Natusch Busch about a coup.

Their idea was to overthrow President Walter Guevara Arze, keep the recently elected Congress open to give the new government a certain democartic facade and, if possible, to avoid a strong reaction from Washington.

Their motive: power and influence, money and jobs, which Guevara had denied them.

Guevara got wind of the plotting almost immediately, according to his son and chief aide, Walter Guevara Anaya. In an interview Tuesday walter Hijo (son), as he is known here, outlined both the conspiracy and his father's frantic efforts to outflank it.

Walter Hijo described Bedregal and Fellman as "very intelligent and very cynical. They tell you they are going to stab you in the back and then they proceed to do it."

For his part, Nausch is described by diplomats who know him as an ambitious man whose chief aim was to seize power and retire a whole generation of Army officers who had prevented colonels like himself from advancing.

Asked if Natusch is intelligent, one diplomate who knows him well said "that with that we enter into the unknown. He is a blind date."

Walter Hijo knew Tuesday that if his father did not succeed in fashioning a coalition Cabinet, including members of the three main coalitions that completed in elections in July, the coup would come this week.

"You must be the only person n the country who doesn't know that Busch is ready to overthrow us Thursday or Friday night. The coup is prepared and ready," Guevara told that reporter on Tuesday.

His estimate was almost precise. The coup came 24 hours earier than expected.

Coups, of course, are common in Bolivia -- more than 190 in its 155-year history as an independent nation. There have been three coups and five different presidents during the last 16 months.

This is not a record. Bolivia had five presidents in 24 hours in 1971.

But the coup that overthrew Guevara this morning was the first in more than a decade that exchanged a civilian president for a military one. It also ended less than three months of democratic government, which Guevara desperately tried to salvage.

The coup leaders are members of the National Revolutionary Movement whose leader is Victor Paz Estenssoro, twice president of Boliva and a major political figure here. Paz just missed obtaining a majority of the votes in last July's presidential election. He was out of Bolivia when Bedregal and Fellman first approached Col. Natusch.

On his return almost two weeks ago, Paz was told of the coup plotting and reportedly decided that it was neither in his nor the country's interest.

Paz met with Guevara on Oct. 23 to tell him that he was against the coup. It was the same day that Paz and other leaders lunched in the U.S. embassy with secretary of State Cyrus Vance, here for the General Assembly of the Organization of American States. Vance made it clear that the United States wanted Bolivia's democratic government to continue.

After their meeting, Guevara asked Paz if he would tell Col. Natusch of his oppostion to the coup. The three met in Guevara's office Oct. 24.

Natusch reportedly denied that he was plotting a coup and Guevara demanded a statement to that effect. Natusch, who had declined an invitation to Tuesday's lunch with Vance, delayed until last Friday, when he finally issued a statement saying it was "irresponsible" that some politicans were saying he was "involved in political activities."

Meanwhile, Guevara -- an interim president because of inconclusive elections in July -- was receiving overtures from the military to be part of two other possible coups. Both would have left him in the presidency but would have closed the congress -- which the older generals were frightened of because a number of congressmen had begun investigating corruption and human rights abuses under past military governments.

Guevara, according to his son, refused the overtures because he did not want to close the congress and short-circuit the democratic experiment he was trying to save.

"My father is a strange character, " Guevara Hijo said. "He would rather go home [than close the congress.] It wouldn't be the first time he turned down a coup."

But by yesterday afternoon, the military had agreed to support whomever moved first to seize power -- a crucial step because otherwise there might have been a fight among the armed forces and a real bloodbath.

Natusch seized his opportunity. Troops from one of two regiments in La Paz moved about 4 a.m. The tanks rumbled up to surround the presidential palace and the congress. By 5 a.m., Bolivia's experiment with democracy was over.