The 1983 Portuguese legislative election took place on 25 April. The election renewed all 250 members of the Assembly of the Republic.
The last election, in October 1980 had been won by a right-wing coalition, the Democratic Alliance (AD) and Francisco Sá Carneiro had retained office as Prime Minister with an increased majority.
However, Sá Carneiro, along with other important members of the coalition, died in an aircrash only two months after the election, on 4 December 1980. Such happenings caused a massive political instability and Francisco Pinto Balsemão, a senior official of the Social Democratic Party, the largest party in the Alliance, became Prime Minister. However, Balsemão's governments were very unstable and after the 1982 local elections results, he resigned as Prime Minister. The Social Democratic Party proposed possible names for Prime Minister to President of Portugal António Ramalho Eanes, but the President refused them and decided to call a snap election for April 1983.
The election was won by the Socialist Party with 36 percent, and Mário Soares was nominated Prime Minister. However, the Socialists lacked a majority in the Assembly of the Republic and were forced to form a coalition with the Social Democrats, which achieved 27 percent, in what was called the "Central Bloc". Although this coalition allowed Soares to govern, several members of both parties were against it, and internal attacks led to the collapse of the coalition after less than two years. In the election that followed, the Communist-dominated United People Alliance lost 3 MPs and the Democratic and Social Center, after the dissolution of the Democratic Alliance, was now alone in the Parliament with 30 MPs, a loss of 16. The election marked the beginning of a process of bi-polarization of Portuguese politics.
This was the last legislative election to be won by the Socialist Party until 1995.
Background.
In October 1980, the Democratic Alliance (AD), led by Francisco Sá Carneiro, was reelected with reinforced majority but it was cut short with the death of Sá Carneiro, his partner Snu Abecassis, his Defense minister Adelino Amaro da Costa and his wife, plus other crew members, in a tragic plane crash in Camarate, Loures, shortly after taking off from the main runway of Lisbon Airport. This tragic air crash sparked a series of conspirancy theories, mainly because of Portugal's involvement in the Iran–Iraq War and the supply of weapons to both Iraq and Iran.
Following the death of Sá Carneiro, Diogo Freitas do Amaral, CDS leader, became interim Prime Minister until the election of a new PSD leader. In January 1981, the PSD elected Francisco Pinto Balsemão as leader and he became Prime Minister.
Government fall.
Pinto Balsemão had a lot of problems in leading the government, as he lacked support from many senior members of his party, like Aníbal Cavaco Silva, former Finance minister under Sá Carneiro, and several ministers also resigned. Moreover, the right-wing policy was criticized by the left-wing and by the trade unions, and in February 1982, the General Confederation of the Portuguese Workers, with the support of the Communists, called for a general strike that shook the government. The wave of resignations among Balsemão's ministers continued and by the end of 1982, and also influenced by the AD's bad results in the 1982 local elections, Balsemão himself also resigned. 
The Social Democratic Party proposed, to President Ramalho Eanes, a government led by Vítor Crespo, but President Eanes rejects the proposal citing that the political conditions were just too deteriorated, thus he decided to dissolve the Parliament and call an election for April. Shortly after, the AD was dissolved as PSD, CDS and PPM decided to contest by their own the April snap election.
Leadership changes and challenges.
CDS 1983 leadership election.
After the dissolution of the Democratic Alliance (AD), Diogo Freitas do Amaral resigned from the party's leadership, and a new congress to elect a new leader was called. Two candidates were on the ballot, Francisco Lucas Pires and Luís Barbosa, with Lucas Pires being elected as new party leader.
PSD 1983 nomination selection.
Just like CDS, after the collapse of the AD coalition, the then PSD leader Francisco Pinto Balsemão announces he would not run for the leadership of the party. Shortly after, Carlos Mota Pinto is selected by the PSD as the party's candidate for Prime Minister.
Electoral system.
The Assembly of the Republic has 250 members elected to four-year terms. Governments do not require absolute majority support of the Assembly to hold office, as even if the number of opposers of government is larger than that of the supporters, the number of opposers still needs to be equal or greater than 126 (absolute majority) for both the Government's Programme to be rejected or for a motion of no confidence to be approved.
The number of seats assigned to each district depends on the district magnitude. The use of the d'Hondt method makes for a higher effective threshold than certain other allocation methods such as the Hare quota or Sainte-Laguë method, which are more generous to small parties.
For these elections, and compared with the 1980 elections, the MPs distributed by districts were the following:
Parties.
The table below lists the parties represented in the Assembly of the Republic during the 2nd legislature (1980–1983) and that also contested the elections:
Opinion polling.
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Aftermath.
Fall of the government.
The Central Bloc government had become deeply unpopular by 1984, with the consequences of the International Monetary Fund (IMF) bailout to save public finances and the economy hitting hard on the population. The budget cuts and increasing poverty were creating deep disagreements between PS and PSD, but also within both parties rifts were being formed. In the Social Democrats, these rifts came to a breaking point in February 1985 with party leader Carlos Mota Pinto resigning and announcing he would contest the next leadership ballot. But, Mota Pinto died unexpectedly just days prior to the 1985 PSD congress and Aníbal Cavaco Silva, which was against the Central Bloc, was elected as leader. Shortly after his election as party leader, Cavaco Silva withdraws the PSD support to the Central Bloc, and the government falls. President Ramalho Eanes decides to dissolve Parliament and call a snap election for 6 October 1985.
References.
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