- Red or green? The Dutch PRO party needs to make a choice.
In 2026, the Dutch Green party, GroenLinks (GL/EGP), and the Dutch social-democratic party, Partij van de Arbeid (PvdA/PES), merged to form one party, Progressief Nederland (PRO). This was the result of more than fifty years of discussions on progressive cooperation. The motivation for the merger was primarily motivated by national concerns, but it has implications on the European level: Should the party join the European Green Party which GL founded, or the Party of European Socialists which the PvdA founded?
To solve this question, the new party has decided to organize a referendum from 18 to 25 September. This important moment for PRO creates an opportunity to discuss the role and character of the two parties.
European political parties
European political parties play an important role at the European level. Which European political party a party joins determines which positions it gets in the European Parliament. It also matters for decision-making within the European Council, as the different government leaders of the same European party meet before summit meetings. The European Socialists currently have four prime ministers: in Spain (Pedro Sánchez), Denmark (Mette Frederiksen), Lithuania (Mindaugas Sinkevičius) and Malta (Robert Abela). The European Greens have no prime ministers, but do have ministers under Sánchez, Frederiksen and Sinkevičius.
Parties that are members of the same European party also exchange experiences and ideas through their European political party, the corresponding think tank (formally called European foundation), and bilateral contacts. The choice of a European political party thus matters for the identity and power position of political parties.
The European political parties, such as the PES and EGP, are extraparliamentary organizations through which national parties cooperate. In the European Parliament, their member parties work together in a parliamentary group. The composition of the groups and the parties overlap but the two are not identical.
Comparing party positions from a substantive perspective
In this article, I look at this decision from a substantive perspective. Is PRO a better fit for the European Green Party or the Party of European Socialists? To this end, I use the 2024 Chapel Hill Expert Survey. Every four years, they ask political science experts to position parties on different dimensions. That provides a good picture of the scientific consensus on the substantive policy positions of parties. I also consult other expert surveys, such as the PopuList. Finally, I look at news reporting in the media and, where possible, scientific articles to understand outliers and extreme parties.
Of the many CHES items, I look at the pro-/anti-EU integration dimension, the economic left-right dimension, positions on climate change, positions on same-sex marriage, positions on immigration, positions on the relation between the EU and Russia and positions on the rule of law.
European party landscape
Figure 1 shows the positions of different parties on the economic left-right dimension and the pro-/anti-EU integration dimension. Before we analyse the dimensions, it is useful to consider the parties shown in the Figure, as EU politics can be complex. The red circles are members of the Party of European Socialists. This is the European political party that consists of social-democratic parties such as the Spanish PSOE led by PM Sánchez. The green circles are the members of the European Green Party. This is the European political party that consists of green parties from all over Europe, including the German Bündnis 90/Die Grünen.
The green-red squares show the positions of GL and PvdA. In the 2024 study, experts assessed these parties independently. PRO might end up somewhere between these two parties. Where exactly PRO will position itself is unclear and may depend on all kinds of internal decisions.
The red triangle represents the mean position of members of the Party of European Socialists weighted by their seats in the European Parliament. The green triangle represents the weighted mean of the members of the European Green Party.
But European politics is quite a bit more complex. The Group of the European Greens/European Free Alliance (Greens/EFA)in the European Parliament also includes MEPs that are not members of the European Green Party. It is also the home of Volt, the Czech Pirate Party and regionalist and separatist parties from Spain (like the Catalan separatist ERC and the Galician regionalist BNG, who are representatives of the European Free Alliance). These parties are represented by purple circles. The Group of the Progressive Alliance of Socialists and Democrats (S&D) also includes MEPs from parties that are not members of the Party of European Socialists. Only one of them is in the CHES, DIKO, a centrist Greek-Cypriot nationalist party. This party is represented by the pink circle.
Social-democrats from Slovakia
The dark red circle is the Slovak party Hlas, which is currently suspended as a member of the PES. To understand this, we need to dive into Slovak politics. The PES has seen a major row over Smer. This is the largest government party in Slovakia, led by Robert Fico. Smer was a member of the PES, but was expelled from the PES and the S&D group over a conflict of values: Smer entered government with the ultranationalist SNS for a third time. That is the kind of party that believes that the territory of other countries should be part of Slovakia. Smer opposes sanctions against Russia and has strong ties with Putin due to fossil interests. Fico stepped down as prime minister in 2020 after massive protests following the murder of journalist Ján Kuciak. Kuciak studied the relationship between important figures in the Slovak government and the mob. Smer was suspended in 2023 and expelled from the PES in 2025.
Smer is not the only social-democratic party in Slovakia, however. The other one is Hlas, which is seen as progressive than Smer. After the 2023 elections, Hlas faced a choice between forming a government with the pro-Russian and nationalist Smer or with Progresívne Slovensko (PS/ALDE), the social-liberal, pro-European alternative. Hlas chose Smer and the SNS and was subsequently suspended, but not fully expelled, by the PES. Hlas is represented by the dark red circle.
The gray circles represent other parties in EU member states that are not a member of the Greens/EFA or the S&D groups in the European Parliament.
Economy: European Socialists are more right-wing than Greens
In general, the most important divisions in European politics are between the economic left and right and between pro- and anti-EU parties. We show these in Figure 1. The vertical dimension is the pro-/anti-EU dimension. It concerns the question of whether the party favours European integration or resists it. The horizontal dimension is the economic left-right dimension. This dimension concerns the question whether there should be a greater or a smaller role for the government in the economy.
- Figure 1. (Click to enlarge.)
GL and PvdA both have clearly pro-European and left-wing positions. The European Greens have almost the same position as the PvdA. The Party of European Socialists is on average more right-wing than GL and PvdA. The European Socialists are more right-wing than the European Greens. This is true not only for this general dimension but also for more specific questions on redistribution, taxation and regulation. All in all, when it comes to European integration and economic affairs, PvdA and GroenLinks are both closer to the European Greens than the European Socialists.
Odd ones out
There are three odd ones out in the social-democratic group in Figure 1: the first is the Maltese Partit Laburista (PL) of PM Abela. This party is quite a bit more right-wing than the rest of the social-democrats. The PL are similar to liberals on economic issues. Basically, the Maltese social-democrats embraced the Third Way and never looked back. They are quite enthusiastic about privatization of hospitals, in particular when prominent social-democrats can earn a pretty penny in the process. The PL is not a small player on some insignificant island. They have been in government since 2013 and supply three MEPs (half of the Maltese EP delegation), including a member of the bureau of the S&D group.
The other two parties that deviate strongly are the Bulgarian Socialist Party (BSP) and Saskaņa. The BSP is the successor of the Bulgarian Communist Party from the Soviet period, Saskaņa is a social-democratic party from Latvia. Both parties are quite a bit more Eurosceptic than the mainstream social-democrat. The BSP has two MEPs and Saskaņa one. At the national level, both parties used to be important players in their respective countries, but lost all their seats in recent elections (in 2026 and 2022). All other members of the EGP and the PES are economically left-wing a pro-European.
Climate policy: The European Greens are as climate-oriented as PvdA
In addition to economic questions, the EU plays a major role in climate policies. The vertical dimension in Figure 2 shows the party positions on climate. For reasons of comparability, we kept the horizontal dimension from Figure 1. The vertical dimension shows whether parties are willing to take measures to mitigate climate change when these measures may weaken economic growth, or whether they prioritise economic growth over mitigating climate change.
- Figure 2. (Click to enlarge.)
The GL, like many European Greens, takes a clear green position. The mean of the European Greens, however, is nearly identical in climate matters to the PvdA. The social-democrats are on average quite a bit closer to the centre of the vertical dimension than the PvdA or GroenLinks.
Four social-democratic parties are notably far away from the climate-oriented positions of GL and PvdA: the Maltese PL, the Bulgarian BSP, the Latvian Saskaņa and the Czech SocDem. The latter lost its seats in the European and Czech Parliament after it had helped bring the agrarian business man Andrej Babiš (ANO/Patriots) into power. The climate policy of these parties is similar to that of the German CSU (EPP), the political arm of BMW. All these parties are even less supportive of climate action than the Romanian PSD (PES), a party that argues for reopening of the coal power plants.
Same-sex marriage: GL and PvdA are close to the European Greens
A key feature of left-wing politics is the idea of equality. Allowing same-sex marriage, which the Germans so eloquently call “Ehe für alle” (“marriage for all”), was invented in the Netherlands and then spread all over Europe, like a beautiful rainbow-coloured oil spill.
- Figure 3. (Click to enlarge.)
The vertical dimension in Figure 3 shows the division of parties on same-sex marriage. GL and PvdA occupy an extreme position on the progressive side. They are among the strongest advocates for same-sex marriage. The European Greens are closely aligned to both of them. The variation among social-democrats is greater. Six parties are against same-sex marriage: the Bulgarian BSP, the Latvian Saskaņa, but also the Lithuanian LSDP, de Romanian PSD and the Cypriot-nationalist EDEK from the European Socialists, and the Lithuanian DSVL from the European Greens.
Left parties against equality
The PSD is currently the largest party in Romania. With 10 seats, it is the fourth largest PES member party in the EP. They were in government until spring 2026. The party has its roots in the Soviet-period Romanian Communist Party. Romanian political scientist Sorin Ionita calls the party “nationalist, populist, sensitive to conspiracies, against the West and against the Hungarian minority”. Experts of the PopuList described the PSD as “nominally social-democratic, the PSD is nationalist, economically liberal, socially conservative, and has at times expressed Eurosceptic views”. The party is opposed to same-sex marriage: it favours a traditional definition of marriage and fosters strong ties to the Romanian Orthodox Church. In 2018, the PSD organised a referendum to define a marriage as being between and man and woman in the constitution. Political scientists Gherghina and Silagadze see a tension between the shared European social-democratic ideology, which emphasises equality, and the party denying rights to same-sex couples.
The BSP deserves special attention. In 2024, the party supported a law that forbade “propaganda” of non-traditional sexual orientations and gender identifications. The party spoke out against gender ideology and worried about non-binary persons winning Eurovision. The party opposed a bill to combat domestic violence because it did not just apply to married couples but to all those in intimate relationships. BSP saw this as “an effort to legalise same-sex relationships” or “a third gender”. When in 2022 a cinema in Varna, the third largest city in Bulgaria wanted to screen Close, an award-winning movie about a complicated friendship between two male teenagers, BSP supporters protested, “threw bottles and other objects at attendees” and had the screening cancelled.
This is not to say that the PES as such is anti-LBGT+, rather than they tolerate a party with positions very contrary to their mainstream. In fact, BSP has openly defied the PES majority, calling the idea that the they should align themselves with the PES majority on these matters “Bolshevism [that] was more popular 100 years ago”.
Two outliers from Lithuania
In 2026, the social-democratic LSDP and the DSVL, a member of the EGP, proposed to re-write the article in the Lithuanian constitution that defines marriage as between a man and a woman. They did so to make it more difficult for same-sex partners to be recognised legally as the parents of their kids. The LSDP has been a key party in Lithuanian politics in the last decades. They have two MEPs. Though formally in favour of civil unions, a minority of their national parliament group voted against a bill legalising such unions.
The DSVL is a relatively new party that has only been part of the European Greens since 2024. It has one seat in the European Parliament. This is a green-conservative party that formed as a split in the LVŽS, a green-conservative farmers’ party. The founders represented the moderate wing of the party. This party also voted against civil partnerships in 2022. During the election campaign, they did favour it.
In their opposition to equality, these six are far away from social-democratic and green parties elsewhere in Europe. Their anti-gender ideology rhetoric is more similar to the US Republican Party.
Migration policy: Greens are more liberal than Socialists
Migration is a key issue in many member states and at the European level. The vertical dimension in Figure 4 concerns migration. GL and PvdA both favour a relatively liberal migration policy, with PvdA being a bit more conservative than GL. The member parties of the European Greens are more progressive than the member parties of the PES. The PvdA is slightly closer to the PES than to the EGP. This is one of the few themes where this is the case.
- Figure 4. (Click to enlarge.)
Once again, the variation among the European Socialists is greater than among the Greens. Six social-democratic parties are quite a bit more conservative than the mainstream in the PES. This includes the Bulgarian BSP, the Czech SocDem, the Cypriot EDEK and the Maltese PL.
“Mass immigration is a threat for Europe”
But this also includes the Swedish SAP and the Danish Socialdemokratiet (S). These are not small players: the Danish social-democrats have been in government since 2019. Their leader, Mette Frederiksen, is currently one of the longest-serving prime ministers in the EU. They are often cited as the prime example of a social-democratic party with conservative positions on migration. Frederiksen has said: “I consider this mass migration into Europe as a threat to the daily life in Europe.” That is the kind of language we are used to from the radical right.
The policy of the Danish social-democrats is focused on making Denmark so unattractive for asylum seekers that no one wants to come to the country. Asylum seekers need to hand over personal possessions when they enter the country. The party also uses harsh anti-Islamic rhetoric. The Danish social-democratic minister of immigration has called for outlawing the Muslim call to prayer as some parts of Denmark resemble “a suburb of Islamabad”. The SAP, the largest party in Sweden, has taken over this line from their Danish sister party.
Calling for “lethal means” to stop immigrants
With the Greens, the DSVL again deviates from the progressive line. Between 2024 and 2025, the DSVL governed together the LSDP and the party Nemuno Aušra, a right-wing populist, pro-Russian Eurosceptic party whose leader made antisemitic statements. After that government collapsed due to a conflict within the LSDP, the LSDP and Nemuno Aušra continued governing together without the support of the DSVL. In 2026, this government also collapsed due to disagreements between the two parties. The DSVL returned to government together with the LSDP and the farmers’ party LVŽS.
All three favour a restrictive migration policy, in particular oriented at strengthening the Belarussian border. The minister of home affairs, responsible for migration is Martynas Katelynas (LSDP). He previously was a member of the far-right Nacionalinis Susivienijimas and called for “lethal means” to stop immigrants.
EU-Russia relations: Pro-Russian elements in the PES
The relation between the EU and Russia is of vital importance for Europe given the Russian invasion of Ukraine. The CHES asked experts whether parties favour defence investments to deter Russian aggression or whether they favour trade and diplomacy to improve EU-Russia relations. Figure 5 shows these party positions. GroenLinks, the PvdA, and the European Greens favour defence investments. The European Socialists are on average closer to the centre. That is in par because the second-largest party in the PES, the Italian Partito Democratico, is strongly opposed to defence investments.
- Figure 5. (Click to enlarge.)
The PD is not the only party in the PES with this position. The PL, BSP and Saskaņa also oppose defence investments. The last two parties are clearly pro-Russian. Saskaņa is the party for the Latvia’s Russian minority. Until 2017, the party had a cooperation agreement with Yedinaya Rossiya, the party of Putin. The BSP is also pro-Russian: the party opposed arming Ukraine and sanctions against Russia. Within the European Greens, the Portuguese party Livre is opposed to defence investments, but it has no MEPs.
Rule of law: Greens more unified than PES
Finally, there are big debates about the state of democracy and the rule of law in Europe. Radical right parties are undermining the rule of law all over Europe. But they are not the only parties that do so. To examine parties’ views about the rule of law, we look at an item from the CHES on whether the executive should have power over the judiciary or whether they should be independent. We depict this dimension on the vertical dimension in Figure 6. The parties that strongly favour an independent judiciary include GL, the PvdA, and the European Greens.
- Figure 6. (Click to enlarge.)
The mean of the PES is quite a bit higher. The diversity is also greater among the Socialists than the Greens. This is partially the result of the parties that are above the line, i.e. favour executive control over the judiciary. This includes the Bulgarian BSP, the Romanian PSD, the Maltese PL, but also the Spanish PSOE.
Undermining the rule of law
The Romanian PSD was one of the driving forces behind the dismantling of the Romanian system of rule of law between 2017 and 2019. The government proposed a decree that included proposals to limit the autonomy of judges and, in the words of the British newspaper The Independent, was aimed at “decriminalising corruption”. This led to major protests. The leader of the social-democrats, Liviu Dragnea, was forced to resign and was ultimately convicted for corruption.
The Maltese PL also scores high on wanting to limit judicial independence. The PL is haunted by the murder of the journalist Daphne Caruana Galizia in 2017. Before her death, she was studying tax evasion by people around then prime minister Joseph Muscat (PL) on the basis of the Panama Papers. In 2020, Muscat stepped down after protests when he wanted to pardon people allegedly involved with the murder. He is currently prosecuted in connection to another corruption scandal involving hospital privatisation. Meanwhile, the murder of the journalist keeps haunting also his successor as prime minister, Roberto Abela.
The high score for the PSOE is possibly the result of the corruption scandals that have embroiled the party: there are cases against a former PSOE prime minister, a former organisation secretary and a former minister. PSOE leader and prime minister Sánchez considers some of the prosecutions to be politically motivated. The PSOE is not a small player in the PES: It is the largest party in the S&D group, provides the group chair and the prime minister of one of the largest EU member states.
The European Socialists are the only political family that has to deal with corruption. The green-conservative DSVL was also hit by a scandal: DSVL founder, party leader, parliamentary speaker and former prime minister Saulius Skvernelis faces a bribery charge. Despite denying allegations, Skvernelis has asked for his parliamentary immunity to be lifted and has left the DSVL.
Conclusion: Overall, PRO is closer to the EGP than the PES
On themes as diverse as the economy, EU integration, climate, LGBT+ rights, EU-Russia relations and the rule of law, experts place the Dutch PvdA (as well as GroenLinks) closer to the European Green Party than the Party of European Socialists. Only with regard to migration, experts place the PvdA closer to the PES average than the EGP average, while GL is closer to the EGP. When looking at policy substance, PRO is thus closer to the EGP than to the PES.
The Greens appear to be a very cohesive group around a set of shared, pro-European, progressive, green and left-wing ideas. The European Socialists, by contrast, appear to be a big tent where there is space for many different flavours, including parties that are rather distant from social-democratic ideals on economic, ecological, moral and cultural issues.
Cohesive Greens, big-tent PES
The PSD, the largest party in Romania, stands out here: This party deviates from the social-democratic consensus on issues like the equal treatment of LGBT+ persons, the relationships with Russia and the rule of law. But also the Danish social-democrats led by prime minister Frederiksen, the Latvian LSDP of prime minister Sinkevičius and the Maltese PL of prime minister Abela deviate from the progressive course of the PES. The same is true for the PD and the SAP, the leading opposition parties in Italy and Sweden. Of the six largest parties in the PES, four deviate markedly from the rest of the S&D group on at least one issue.
Perhaps this tension is clearest if we look at the recent row between Sánchez and Frederiksen about the events in Ceuta. While Frederiksen decided to align herself with the Italian radical right-wing prime minister Giorgia Meloni (FdI/ECR) to suspend Spain’s membership of the Schengen Area, the Spanish and Italian social-democrats wrote: “It is unacceptable that, while another European partner was facing exceptional pressure, a member of our own political family chose to align themselves – in a coordinated manner – with Italian Prime Minister Giorgia Meloni, who had just decided to suspend Schengen in a purely propagandistic move, given that there is no freedom of movement from Ceuta into the EU.” Within the Greens there is only one odd one out: The green conservative DSVL differs from the European Greens when it comes to migration and LGBT+ rights. They are quite similar to the social-democratic LSDP, with which they are in government.
In the end, it is a political question
That PRO is more closely aligned with the Greens than the PES, is also evident from a recent analysis of voting behaviour: When Socialists and Greens vote differently in the European Parliament, PRO is twice as likely to vote with the Greens/EFA as to vote with the S&D group.
It is important to note, however, that this analysis says nothing about the question of which European family is strategically the most attractive for PRO. The PES has heads of government (Frederiksen, Sánchez, Sinkevičius and Abela – though they might not be best of friends), and the S&D is the second largest group in the EP. Science cannot answer what is, in the end, a political question.
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Simon Otjes is an Associate Professor for Dutch Politics at the University of Leiden. |
This article was originally published in Dutch on the blog StukRoodVlees.
