Parliamentary elections were held in Chile on 4 March 1973 to choose all 150 members of the Chamber of Deputies and 25 of the 50 members of the Senate.Dieter Nohlen (2005) Elections in the Americas: A data handbook, Volume II, p262 They took place midway through the presidency of Salvador Allende, a Marxist who had been elected in 1970 with about 36 percent of the vote at the head of the Popular Unity coalition. The opposition Confederation of Democracy (CODE), an alliance led by the National Party and the Christian Democratic Party, hoped to win the two-thirds majority in Congress needed to remove Allende from office.

CODE won a majority of the vote, with about 55.5 percent, and of the seats, taking 87 of 150 in the Chamber and 30 of 50 in the Senate. It was nonetheless unable to secure the two-thirds majority in the Senate needed to remove Allende. Popular Unity won about 44 percent of the vote, 63 deputies and 19 senators, a stronger result than most observers had expected, though close to what the same parties had won in the 1969 parliamentary election. Turnout of about 81 percent of registered voters was the highest of the pre-1973 democratic era.

Opposition figures later alleged that the vote had been tainted by fraudulent registrations, an accusation that government officials rejected and that a congressional investigative commission never resolved. The election was the last held before the military coup of 11 September 1973. After the coup Congress was dissolved, the electoral registers were declared void and then destroyed, and Chile did not hold another parliamentary election until 1989.

Background Since the early 1960s, Chile had experienced sustained inflation, which continued under the Allende government and was a major factor in the economic crisis that began in 1972. In response, the government implemented the Vuskovic plan, which aimed to increase state control over the economy through nationalizations and official price-setting within a planned economy. Shortages of supplies accompanied the inflation.

Inflation and the wave of expropriations of private companies also produced discontent among the upper and middle classes. This culminated in the October 1972 strike, which sought to halt expropriations, establish market-adjusted prices, return companies to private owners and protect private property. The government faced numerous demonstrations against its policies and the high cost of living. According to historian Joaquín Fermandois, the right-wing parties and the Christian Democratic Party largely supported and took part in these mobilizations, seeking to discredit the government's policies, isolate it socially, and pressure it to change course or resign.

Allende had won the 1970 presidential election with only 36.3 percent of the vote in a three-way race, and Popular Unity lacked a majority in Congress. If the opposition could win two-thirds of Congress, it might have been able to roll back the government's program and perhaps impeach the president, which gave the March 1973 elections unusual stakes.

Electoral system Deputies and senators were elected by proportional representation using the D'Hondt method. The electoral system generally prohibited electoral pacts between political parties, but in June 1972 the Election Certification Tribunal ruled that parties could form federations and confederations, effectively allowing them to present joint electoral lists. This mechanism was used for the 1973 election by the Confederation of Democracy (CODE), Popular Unity (UP), and the Popular Socialist Union (USOPO).

Voters cast a preferential vote for an individual candidate on a list. In each constituency, the votes received by the candidates belonging to the same list were added together to determine the number of seats won by that list under the D'Hondt method. The seats won by each list were then assigned to its candidates according to their individual preferential vote totals.

Reforms adopted in 1958 had introduced compulsory and permanent voter registration and a single official ballot listing all candidates.

The 150 deputies were elected for four-year terms in 27 multi-member constituencies based on departments. Senators served eight-year terms, with half of the Senate normally renewed every four years. This election saw 25 of the 50 Senate seats up for election, with five senators chosen from each of five groupings of provinces: Atacama and Coquimbo; Santiago; Curicó, Talca, Linares and Maule; Biobío, Malleco and Cautín; and Chiloé, Aysén and Magallanes. The other 25 senators, elected in 1969, kept their seats.

Voter registration and turnout The approval of Law No. 17,284 in 1970 led to a rise in voter participation. These elections marked the implementation of the reform on a nationwide scale, resulting in the highest level of voter engagement within the previous democratic system. Around 80.6% of the electorate (equivalent to 44% of the national population) were registered to vote, and 81% of the registered voters (approximately 3.7 million individuals) exercised their right to vote. According to the official count there were 4,510,060 registered voters and 3,687,105 ballots cast in the Chamber election, a turnout of 81.75 percent.

Political parties and electoral pacts

Before the elections several political parties underwent internal divisions and splintered into smaller factions. While the majority of Christian Democrats led the Freiist faction, other groups formed the Popular Unitary Action Movement (MAPU) and the Christian Left, which later joined the Popular Unity. The Christian Left emerged after the Christian Democrats, National Party and Radical Democracy backed a common independent candidate in a by-election in Valparaíso and Quillota, which led eight Christian Democratic deputies and several party leaders to leave the party. Dissident radicals from the central leadership divided into two factions: Radical Democracy, a traditional right-wing group, and the Radical Left Party, a moderate social democratic faction that initially supported Allende but moved into opposition in April 1972.

In June 1972 the Election Certification Tribunal ruled that the electoral law allowed the creation of "federated parties", a device that in effect restored the electoral pacts. In anticipation of the elections, the Confederation of Democracy was organized on 6 July 1972. It was a coalition of center and right-wing parties, grouped in the Federation of Democratic Opposition and the National–Radical Democracy Federation, comprising the Christian Democrats, National Party, Radical Left Party, Radical Democracy, and the National Democratic Party, all opposed to Popular Unity. Popular Unity, which brought together the parties supporting the government, was constituted as a federation on the same day. Apart from these two primary electoral pacts, the Popular Socialist Union (USOPO), a small left-wing group that had split from the Socialist Party, also participated in the elections.

On 6 November 1972 a drawing at the Electoral Registry Directorate assigned the order of the lists on the ballot: letter A went to CODE, B to Popular Unity and C to the Popular Socialist Union. Ballots were color-coded by office: light blue for senators, yellow for deputies, and pink for the extraordinary municipal council elections held in 13 communes.

Candidates In all, 361 candidates stood: 322 for the Chamber of Deputies and 39 for the Senate.

Pact and partiesCandidatesDeputiesSenators A. Confederation of Democracy149 22 Christian Democratic Party PDC65 11 National Party PN51 6 Radical Democracy DR13 3 Radical Left Party PIR16 2 National Democratic Party PADENA4 - B. Popular Unity141 17 Socialist Party PS39 5 Communist Party PCCh34 5 Radical Party PR25 5 Popular Unitary Action Movement MAPU18 2 Christian Left IC14 - Independent Popular Action API11 - C. Popular Socialist Union32 - Popular Socialist Union USOPO32 -Total candidates322 39Source: El Mercurio, via Chilelectoral.

Municipal by-elections On the same day, extraordinary elections for regidores (municipal councilors) were held in 13 communes. Two of them, Pueblo Hundido and Entre Lagos, were newly created communes electing their first five-member councils; the others (Salamanca, Quilicura, San José de Maipo, Calera de Tango, Rengo, Malloa, Hualañé, Paredones, Coelemu, Lumaco and Puerto Varas) held elections to fill seats left vacant by the death of an incumbent. Elections were also due in the new commune of Tirúa, but it was created after the deadline for registering candidacies had passed, so no vote was held there.

Campaign

The official campaign period ran from 18 January to 2 March 1973. A contemporary account described a campaign preceded by even more threats, insults and predictions of triumph or doom than usual in Chilean politics. On 14 November 1972 the Electoral Registry Directorate set the maximum daily time each list could buy for paid propaganda on radio stations in each province: 20 minutes per list in the 16 provinces where all three lists were running, and 30 minutes per list in the nine provinces where only CODE and Popular Unity appeared.

The campaign unfolded amid hostility between supporters of the government and its opponents. Between 6 and 31 January 1973, 690 people were detained for unauthorized propaganda (449 from CODE and 241 from Popular Unity), and 15 were arrested for illegally carrying firearms (9 from CODE and 6 from Popular Unity).

Opinion polls The political, social and economic crisis appeared to give the opposition an advantage, and polls published before the vote generally showed it ahead, with estimates of its support ranging from about 45 percent to 62 percent depending on the pollster and the share of undecided respondents.

PollsterDate CODE UP CEDEM Dec 197247.4% 39.5% 13.1% M. Hamuy Jan 197349.4% 36.6% 8.9% CEDEM Feb 197345.5% 37.4% 17.1% IDOP Feb 197361.6% 31.2% 7.2% Investigaciones Feb 197351.8% 43.7% 4.8%

Conduct President Salvador Allende voted at 10:06 a.m. at Liceo No. 14 in Las Condes, where Interior Minister and Army commander-in-chief Carlos Prats also cast his ballot. The Gabriela Mistral Building served as the Interior Ministry's vote-counting center and also housed polling stations for women voters from central Santiago.

Television and radio stations offered extended coverage. Televisión Nacional de Chile began broadcasting at 8:00 a.m. with a studio linked to the counting center and ended with a political forum, while Canal 13, in partnership with Radio Cooperativa, opened at 9:00 a.m. with a Mass celebrated by Cardinal Raúl Silva Henríquez and combined mobile units, film dispatches from the provinces and a link to the counting center. Canal 9, the University of Chile's station, began at 10:00 a.m. and broadcast jointly with Radio Corporación and its network of affiliated stations around the country.

Results The election produced a split verdict. The opposition kept its majority, but Popular Unity won more votes than expected, about 44 percent against CODE's roughly 55.5 percent. Contemporary observers described this as an unprecedented gain for a Chilean government in a midterm election, and the result denied the opposition the two-thirds majority it needed to remove the president. Although the outcome was widely described as a surprise, the share of the vote won by the left-wing coalition was almost the same as that won by the same parties in the 1969 parliamentary election (43.84%). The resulting balance of power would prevent the Senate from constitutionally accusing President Allende.

Senate