The 1980 Portuguese legislative election took place on 5 October. The election renewed all 250 members of the Assembly of the Republic. In January 1980, the Democratic Alliance, which had won the previous election, on 2 December 1979, entered office with Francisco Sá Carneiro leading the government. However, this election was an extraordinary election and because of Fixed-term Parliament rules, in 1980, another election was held. The Democratic Alliance (AD) won, again, and increased the majority they had achieved 10 months before, in December 1979. The AD won almost 48 percent of the votes and gathered 134 seats, six more. The Socialist Party (PS), now leading a broad coalition called Republican and Socialist Front, got basically the same vote share and seats as in 1979. The Communist led alliance, United People Alliance (APU) lost some ground, gathering almost 17 percent of the votes, 2 percentage points lower than 10 months earlier. Turnout was one of the highest ever, almost 84 percent, and in terms of ballots cast, the more than 6 million votes cast was a record in Portuguese elections for 44 years after being surpassed in the 2024 legislative election.

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 1979 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 second half of the 1st legislature (1976–1980), as the 1979 election was a national by-election, and that also contested the elections:

Campaign period

Party slogans

National summary of votes and seats

! rowspan="2" colspan=3 style="background-color:#E9E9E9" align=left|Parties ! rowspan="2" style="background-color:#E9E9E9" align=right|Votes ! rowspan="2" style="background-color:#E9E9E9" align=right|% ! rowspan="2" style="background-color:#E9E9E9" align=right|± ! colspan="5" style="background-color:#E9E9E9" align="center"|Seats ! rowspan="2" style="background-color:#E9E9E9;text-align:right;" |MPs %/ votes % ! style="background-color:#E9E9E9;text-align=center|1979 ! style="background-color:#E9E9E9;text-align=center|1980 ! style="background-color:#E9E9E9" align=right|± ! style="background-color:#E9E9E9" align=right|% ! style="background-color:#E9E9E9" align=right|±

Distribution by constituency

!rowspan=2|Constituency!!%!!S!!%!!S!!%!!S!!%!!S!!%!!S!!%!!S !rowspan=2|Total S !colspan=2 | AD !colspan=2 | FRS !colspan=2 | APU !colspan=2 | PSD !colspan=2 | PS !colspan=2 | UDP

Maps

Aftermath

Death of Francisco Sá Carneiro

Just two months after winning the 1980 elections, and while campaigning for the Democratic Alliance's candidate for the December 1980 Presidential election, Prime Minister Francisco Sá Carneiro and his Defense minister Adelino Amaro da Costa, along with their spouses Snu Abecassis and Maria Vaz Pires, respectively, and the plane's pilot, died in tragic air crash when the small aircraft they were on board crashed and burned 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' involvement in the Iran–Iraq War and the supply of weapons to both Iraq and Iran. Several investigations surrounding the crash were conducted and the official cause of the crash is still a matter of intense debate. Diogo Freitas do Amaral was appointed as Interim Prime Minister until the election of Francisco Pinto Balsemão as PSD leader and subsequent nomination as Prime Minister.

Fall of the government

The Balsemão governments were very unstable due to lack of leadership and deep disagreements between the three parties that composed the Democratic Alliance (AD). In the 1982 local elections, the AD was able to gather 42 percent of the votes, against the 31 percent of the PS and 20.5 percent of APU, but suffered loses and many within the coalition, mainly Diogo Freitas do Amaral, labeled the results as a disaster. With this background, Pinto Balsemão resigned as Prime Minister and the PSD proposed names for Prime Minister to President António Ramalho Eanes. However, President Eanes refused to swear in a new AD government and dissolved Parliament by calling elections for 25 April 1983.