However, the Congress failed to elect a candidate after three ballots and instead selected Senate leader Wálter Guevara to serve as Interim President for a year on 8 August.

[4] General elections had previously been held on 9 July 1978, the first since 1966, with several military coups taking place during the late 1960s and early 1970s.

[2] Although Juan Pereda of the Nationalist Union of the People won the presidential elections, more votes were cast than there were registered voters.

[5] After examining a number of allegations of fraud and other irregularities, the Electoral Court decided to annul the results on 20 July.

Pereda himself was overthrown by yet another military coup in November, which saw General David Padilla assume the presidency,[7] promising to hold fresh elections in July the following year.

In addition to Siles Zuazo and Paz Estenssoro was Hugo Banzer who just the previous year had seen his 7-year dictatorship come to an end.

The final major candidate was Marcelo Quiroga Santa Cruz of the Socialist Party-1 (PS-1) who in the previous election had achieved a minuscule 0.43% of the vote.

As such, the MNR and its splinters returned to being the primary protagonists of Bolivian politics, a fact which had not been the case since the deposition of Paz Estenssoro in 1964.

Hernán Siles Zuazo had won the plurality of the popular vote but not by a clear enough amount to be the obvious choice for president.