A single political party winning majority of legislative seats is - in theory - very difficult under proportional representation system.

Examples I am aware:

  • Portugal 2022: The Socialist Party won 112 out of 230 seats under party-list PR system, giving PM Antonio Costa an outright majority. Context unclear.

  • New Zealand 2020: The Labour Party won 65 out of 120 seats under MMP system, giving PM Jacinda Ardern an outright majority. The election was widely framed a verdict on Labour's response to COVID-19.

  • Sweden 1968: The Social Democrat won 125 out of 233 seats under party-list PR system, giving PM Tage Erlander an outright majority. Context unclear.

Are there other examples in history where it happened? What are the circumstances that caused political parties to achieve such electoral performance?

2 Answers 2


This happened a few times in Austria, though not recently on the national level.

Here is a diagram of National Council election results since Austria became a republic. If that diagram is correct: In 1920 and again from 1971 the National Council had 183 seats, of which a majority is 92 seats, which the SPÖ (red, Sozialdemokratische Partei) achieved in the 1970s under Bruno Kreisky. Between that, the National Council had 165 seats, of which a majority is 83 seats, achieved by the Christlichsoziale Partei (pre-WW2) and its successor, the ÖVP (after WW2) (both black) a few times too.

Those two large parties have, as can be seen on that diagram, become a lot less relevant in more recent decades.

How was it achieved? The best sources I have available are textbooks that were used in Austrian schools which explain the following as factors for Bruno Kreisky's success.

According to "Zeitbilder 4" (1st edition reprinted in 2006, ISBN 3-209-03767-1):

  • The SPÖ was able to win over some bourgeois and liberal voters and changed from being a "pure workers' party" to a "left-wing people's party".
  • Kreisky buried the traditional animosity between church and party and declared that every religious person could also be a socialist.

According to "Zeitbilder 7&8" (1st edition from 2006, ISBN 978-3-209-05449-4):

  • Kreisky stopped using the (in his mind outdated) term "working class".
  • He won over young male voters by shortening mandatory military service.

On the subnational level in Austria, this is more common, including more recently. I can't find such a nice diagram as above, but this table has the results for the Second Republic and this table for the First Republic. You can see for example that absolute majorities for the SPÖ have historically been common in Vienna (where other parties basically just campaign on wanting to be the SPÖ's coalition partner) and for the ÖVP in many other states like Tyrol, Vorarlberg and Lower Austria. This is mainly because the SPÖ is the traditional representation of the working class (large proportion of the population in Vienna) and the ÖVP that of those who work in farming or tourism (many people in rural areas).

  • Have Austria always been using the same electoral system? From the graph you cited, it looks like there might have been some changes half way thtough, causing parties to fragment. Dec 3, 2022 at 4:40
  • 1
    @QuantumWalnut It has to my knowledge and according to my quick research always been a form of party-list proportional representation, only the details have changed. The increased number and diversity of parties that you can see in that graph really is the result of changes in voter behavior, not the voting system. One could probably write an entire book about why that happened; the TLDR is that older generations voted almost exclusively for ÖVP and SPÖ which promised stability, while younger generations were not that satisfied with them anymore at some point.
    – wonderbear
    Dec 3, 2022 at 8:02
  • That's fascinating. Someone should really write a book on it! Dec 3, 2022 at 8:44

This has happened frequently in the German state of Bavaria with the CSU party. In the 2003 election they even managed to get 2/3 of all parliament seats (allowing them to change the state constitution). The CSU lost their absolute majority in the last election in 2018, apartently for only the second time since 1950.

  • 1
    This answer could benefit from an explanation of the reasons for CSU success: There aren't a lot of sources on it but here's an interview (in German). Basically, the CSU has successfully branded itself as the Bavarian party, especially because it ruled Bavaria for decades already. It's also a party that only runs in Bavaria while still maintaining federal influence through its cooperation with the CDU. Also, it's the only party with local structures in the entire state.
    – xyldke
    Dec 2, 2022 at 13:06
  • That's fascinating. Dec 3, 2022 at 4:34

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