Although these major steps were never reversed, observers have regarded the revolution as unfinished because it lost momentum after the first years. The divisions within the MNR seriously weakened its attempt to incorporate the support of the Indian peasants, the workers, and the middle class for the government. In 1952 the MNR was a broad coalition of groups with different interests. Juan Oquendo Lechín led the left wing of the party and had the support of the labor sector. Siles Zuazo represented the right wing and had the backing of the middle class. Paz Estenssoro was initially the neutral leader. Because the majority of the MNR elite wanted a moderate course and the left wing demanded radical change, the polarization increased and led eventually to the destruction of the MNR in 1964.

The country faced severe economic problems as a result of the changes enacted by the government. The nationalization of the mines had a negative effect on the economy. The mines of Comibol produced at a loss because of the lack of technical expertise and capital to modernize the aging plants and nearly depleted deposits of low-grade ore. Declining tin prices on the world market contributed to the economic problems in the mining sector. Nevertheless, workers in the management of Comibol increased salaries and the work force by nearly 50 percent.

The decline of agricultural production contributed to the rapidly deteriorating economy during the first years of the revolution. Although anarchy in the countryside was the main reason for the decrease in production, the peasants' inability to produce for a market economy and the lack of transport facilities contributed to the problem. The attempt to increase agricultural production by colonizing the less densely populated valleys was not successful at first. As a result, the food supply for the urban population decreased, and Bolivia had to import food.

High inflation, primarily caused by social spending, also hurt the economy. The value of the peso, Bolivia's former currency, fell from 60 to 12,000 to the United States dollar between 1952 and 1956, affecting primarily the urban middle class, which began to support the opposition.

The bankrupt economy increased the factionalism within the MNR. Whereas the left wing demanded more government control over the economy, the right wing hoped to solve the nation's problems with aid from the United States. The government had sought cooperation with the United States as early as 1953, a move that had given the United States influence over Bolivia's economy. Because of United States pressure, the Bolivian government promised to compensate the owners of nationalized tin mines and drew up a new petroleum code, which again allowed United States investments in Bolivian oil.

During the presidency of Siles Zuazo (1956-60 and 1982-85), who won the election with 84 percent of the vote, United States aid reached its highest level. In 1957 the United States subsidized more than 30 percent of the Bolivian government's central budget. Advised by the United States government and the IMF, the Siles Zuazo regime then in power reduced inflation with a number of politically dangerous measures, such as the freezing of wages and the ending of the government-subsidized miners' stores.

Siles Zuazo's stabilization plan seriously damaged the coalition between the MNR and the COB. The COB called immediately for a general strike, which threatened to destroy an already disrupted economy; the strike was called off only after impassioned appeals by the president. But the conflict between the government and the miners' militias continued as the militias constantly challenged the government's authority. Siles Zuazo faced not only labor unrest in the mines but also discontent in the countryside, where peasant leaders were competing for power. In an effort to quell the unrest, he decided to rebuild the armed forces.

During the Siles Zuazo administration, the strength of the armed forces grew as a result of a new concern for professionalism and training, technical assistance from the United States, and an increase in the size and budget of the military. In addition, the military's role in containing unrest gave it increasing influence within the MNR government.

Although the stabilization plan and the strengthening of the armed forces were resented by Lechín's faction of the party, the first formal dissent came from Walter Guevara Arze and the MNR right wing. Guevara Arze, who had been foreign minister and then minister of government in the first Paz Estenssoro government, split from the MNR to form the Authentic Nationalist Revolutionary Movement (Movimiento Nacionalista Revolucionario Auténtico--MNRA) in 1960, when his presidential hopes were destroyed by Paz Estenssoro's candidacy. Guevara Arze charged that the MNR had betrayed the revolution, and he posed a formidable opposition in the presidential election of 1960.

Conflicts within the MNR increased during Paz Estenssoro's second term (1960-64). Together with the United States and the Federal Republic of Germany (West Germany), Paz Estenssoro endorsed the "Triangular Plan," which called for a restructuring of the tin-mining industry. The plan demanded the end of the workers' control over Comibol operations, the firing of workers, and a reduction in their salaries and benefits; it was strongly opposed by the COB and Lechín's MNR faction.

In 1964 Paz Estenssoro decided to run again for president, using a revision of the 1961 Constitution that would allow for a consecutive term, and he forced his nomination at a party convention. Lechín, who had hoped to become the presidential candidate, broke away to form the National Leftist Revolutionary Party (Partido Revolucionario de la Izquierda Nacional--PRIN). With his support in the MNR dwindling and opposition from the labor sector mounting, Paz Estenssoro accepted General René Barrientos Ortuño as vice presidential candidate. Because most opposition groups abstained, Paz Estenssoro was reelected with the support of the military and the peasants. Paz Estenssoro had come to rely increasingly on the military, whose role as a peacekeeper had made it an arbiter in politics. But this support was to prove unreliable; the military was already planning to overthrow him. Moreover, rivalry among peasant groups often resulted in bloody feuds that further weakened the Paz Estenssoro government.

During its twelve-year rule, the MNR had failed to build a firm basis for democratic, civilian government. Increasing factionalism, open dissent, ideological differences, policy errors, and corruption weakened the party and made it impossible to establish an institutional framework for the reforms. Not even the peasants, who were the main beneficiaries of the revolution, consistently supported the MNR.

Data as of December 1989