Portugal 2022–unexpected majority, but not that rare (for Portugal)

The majority of seats obtained by the Socialist Party (PS) in the recent general election in Portugal was seen as a surprise. Polling generally had not shown a majority as within reach and indeed showed a likely close result. However, Portugal has had relatively frequent parliamentary majorities over the years, despite its proportional representation (PR) system. How unusual was the 2022 outcome?

From 1976 to 2019, the mean seat share for the largest party in Portugal has been 0.478–not a majority, but pretty close. In this election the PS obtained 117 of 230 seats, which is 0.509. (The total includes the four seats for Portuguese abroad.) This is the fifth absolute majority won in 16 Portuguese assembly elections since 1976. Thus in terms of Portugal’s electoral history, the result was not so unusual. How unusual is it relative to what is expected from Portugal’s PR system?

Portugal’s electoral system has a seat product of around 2400. This is a modest seat product by standards of proportional representation, stemming from a moderate assembly size, S (currently 230; 250 before 1991), and a middle-range district magnitude, M (currently 10.5 on average), yielding a seat product, MS=2415. For such a seat product, the expected largest party seat share is 0.378, derived from the formula expecting this share to be (MS)–1/8. Thus Portugal’s actual largest party seat share has averaged 1.26 times the seat product model prediction.1 This indicates that while Portugal’s electoral system is not expected to produce a high degree of fragmentation (38% of the seats is a decent sized largest party2), actual Portuguese politics supports a more de-fragmented party system–at least so far–than what its electoral system could sustain.

As for votes, the associated formula of the seat product model implies we should expect the largest to have 35.4% of the votes, but the average has been 41.8% instead. In this election the PS won 41.7%. So, whatever people expected, it was a pretty ordinary voting result by the standard of Portuguese electoral history. There was a somewhat higher boost for the largest party, however, than the norm. The average advantage ratio (%seats/%votes) has been 1.14; in this election it was 1.22. I would guess that this larger seat bonus for the largest party comes in significant part from the main rival for national power, the Social Democrats (PSD, actually a center-right party) losing votes to a farther right-wing/nationalist party, CHEGA. The latter party was the big gainer in votes and seats in the election, as it had only one seat from 2019 but won 12 in this election. However, it had a very low advantage ratio, with its 5.31% of seats coming on 7.15% of votes, for a ratio of 0.74. Its votes thus did not translate efficiently into seats, which may have helped the PS harvest more seats than normally would be the case for a party with just over 41% of the votes given Portuguese electoral laws.3


  1. The mean actual largest party seat share in a sample of 634 simple electoral systems is only 1.048 times the model prediction; for PR systems the model is even better, with a ratio of 1.033. So a ratio of 1.26 indicates a strong degree of politics being needed in addition to institutions to explain an outcome. Less than a quarter of PR elections have ratios that high or higher.
  2. The mean largest party seat share for the sample of 280 PR elections in parliamentary (or semi-presidential) democracies that I am working with happens to be 38.2%.
  3. Relative punishment of smaller parties is an inherent feature of the system’s moderate seat product. For instance, in this election the significantly smaller Liberal Initiative won 3.5% of seats on just under 5% of votes. The wasted votes by smaller parties have to go somewhere; given that Portugal uses the D’Hondt formula, the result will tend to be generally more favorable to the largest party than it would be with other PR formulas, for a given seat product. (This is not unusual; more than two thirds of all simple PR systems use D’Hondt.) Still, for a party in its range of vote percentage, CHEGA’s advantage ratio is quite low. For instance, in 2019, the Left Bloc and Unitary Democratic Coalition, with 9.5% and 6.3% of votes, respectively, had advantage ratios of 0.86 and 0.82. So CHEGA must have had an unusually inefficient geographic spread for a party of its approximate size. Indeed, skimming the table the Wikipedia page offers for district-level results, it is easy to spot districts where CHEGA received above its nationwide vote share yet won no seats. As a final note on CHEGA, I will add that its single seat in 2019 was won in Lisbon, where the district magnitude is 48, on 2% of the vote.

Party Personnel Strategies is published

Just received: My copy of Party Personnel Strategies: Electoral Systems and Committee Assignments.

A preview of most of Chapter 1 is available for free at Google Books. More details, including the table of contents, can be viewed at the book’s Oxford University Press page.

The back cover has the short summary, as well as some very kind words from other scholars:

The country cases covered in the book, each with its own chapter, are Germany, Japan, Israel, Portugal, Britain, and New Zealand. The research design leverages the electoral-system changes in Japan and New Zealand.

The book develops two “models” of party personnel practices, tested on the patterns of assignment of a party’s legislators to committees, broken down into three categories: high policy, public goods, and distributive. Under the expertise model, parties are assumed to want to harness the perceived expertise of their individual members by assigning them to committees with matching policy functions. We assume all parties in parliamentary democracies would like to achieve such matches, but, depending on features of the electoral system, they may have to trade off fulfilling the expertise model in order to assign according to an electoral–constituency model. Within the expertise model, there are also a series of issue ownership premises, under which parties of the center-right are expected to match experts to high policy and parties of the center-left to public goods (even if they do not expertise-match in other categories). As expected under our theory, the more that an electoral system makes seat-maximization depend on the geographic location of votes (as with FPTP) or on candidate’s personal votes (or both, as with Japan’s former SNTV), the more the electoral–constituency model dominates over the expertise model.

Although not the book’s central theme, a key subtext is that we now probably can take the question mark off of “best of both worlds” regarding the impact of mixed-member electoral systems, at least for the proportional (MMP) variant used in Germany and post-reform New Zealand. These systems show the highest reliance on the expertise model while simultaneously also fulfilling key premises of the electoral–constituency model.

The project was a long time in development. The book arrives thirteen and a half years after the original “central team” (me, Krauss, and Pekkanen) obtained the news that our NSF grant proposal was going to be funded. It was a complex collaboration, involving scholars specializing on each of the cases, who led the data collection and answered many a question we had. The book could never have seen the light of day without their effort. Nor could have been written without the addition to the author team of Matthew Bergman (originally the project’s research assistant, and central data manager, as well as the originator of our issue-ownership premises) and Cory Struthers (who brought new ideas about distributive policy to the author team, and was my first UC Davis Ph.D. student, not counting one who originally started at UCSD before I moved). We also benefitted from numerous other research assistants and the work of several undergraduate students at Davis, who are named individually in the preface.

As foreshadowed previously at this blog, the book is dedicated to one of the most important scholars ever of comparative legislatures, Gerhard Loewenberg, of blessed memory.

Datasets used in the book will soon be made public. They are not quite ready yet (pending review of a planned journal article that will introduce them to the wider public), but I will post a notification when they are available.

Portugal’s general election

Comments invited on today’s general election in Portugal. This election was called early due to the collapse of the outgoing government of Socialist premier Jose Socrates over the country’s financial crisis.

According to The Guardian, “The most recent opinion polls suggest that [opposition PSD leader] Passos Coelho will win and be able to form a government with the support of the rightwing People’s party.”

Portugal’s government collapses

The cabinet of Portuguese premier José Sócrates failed to secure a crucial vote on an austerity package in the Assembly yesterday, and has resigned. Portugal may need to follow Greece and Ireland in seeking a financial stabilization package (or, less charitably, a “bailout”), and could be headed for a snap election.

This case is particularly interesting to me because it is a case of cohabitation in a semi-presidential* democracy that had been going on–and apparently quite smoothly–for a long time.

The Portuguese president, Anibal Cavaco Silva, is from the misnamed conservative party, the Social Democratic Party (PSD). The outgoing PM is from the Socialist Party (PS). President Silva was reelected in January of this year by a wide margin. I mean, really, really wide:

Anibal Cavaco Silva, PSD, 53%
Manuel Alegre Duarte, PS, 19.8%

Obviously, the PM’s party did not make much of an effort to reclaim the presidency. It was also a very low turnout election, held amid the impending financial crisis.

The presidential election was an unusual case of an election during a cohabitation phase when things were clearly already not going well for the country. Yet the president was reelected easily, and apparently the possibility of the president’s using his power to dissolve parliament and change the government (i.e. the PM and cabinet) was not a campaign theme. (See, for example, a Bloomberg report on election day.)

(For the record, in 2006, Cavaco Silva likewise had won an outright majority.)

The comfortable working relationship between the two goes all the way back to Silva’s first election, in 2006. David Samuels and I have the following notation in the dataset for Presidents, Parties, and Prime Ministers (Cambridge, 2010):

Rival Parties- Silva’s campaign had promised to work with Socrates, did not attack the PM during the election, but inherited a PM from a rival party.

Sócrates had been in office since 2005.

Sócrates led a minority single-party cabinet. The PS obtained 37.7% of the vote in the September, 2009, election, winning 96 of 226 seats. This was a substantial drop from the 2005 election (-8.7% in votes and -24 seats), but good enough to remain in power. The president’s PSD won only 30% of the vote and 78 seats in the election. Parties farther to the left saw a greater increase in their votes and seats in the 2009 election than did the PSD. It was, of course, these leftist parties, in addition to the PSD, that defeated Sócrates in the austerity vote.

So now what? Contrary to some popular and academic assessments, the Portuguese presidency is far from powerless (see Amorim Neto and Lobo, 2009).

If negotiations to form a new government in the current parliament are not fruitful, the president could dissolve parliament and call an early parliamentary election. Whether that would put an end to cohabitation, or result in its reinforcement via an Ireland-style implosion of the governing party, is something I certainly am not in a position to predict. In any case, this will be interesting to watch for us students of semi-presidential systems.

* The Portuguese system fits squarely in the subtype of premier-presidential, wherein the outcome of legislative elections is more important for determining the composition of the cabinet than are the preferences of the president.