Coalition-forming in the 20th Bundestag

Article by first-year Sciences Po undergraduate student Yiyang Fang; republished from Sciences Political Review.

On December 8, 2021, Olaf Scholz of the Social Democratic Party (SPD) took up the position of Chancellor of Germany in the 20th Bundestag, ending the Christian Democratic Union’s (CDU’s) 16-year hold over the top office in government.

Scholz’s ascension followed the German federal election on September 26, where his centre-left SPD received 206 of the 736 seats in the Bundestag (27.99% of seats) with its 25.74% of the vote share. The Bundestag is the lower house of Germany’s bicameral federal legislature. The upper house, the Bundestrat, is not involved in the formation of the Cabinet.

This placed the SPD just ahead of the centre-right CDU and its sister party the Christian Social Union (CSU)*, which suffered its worst electoral outcome since 1949 with 24.07% of the popular vote to receive 197 seats in the Bundestag (24.07% of seats). Since 2005, the CDU, under the leadership of Angela Merkel, has led every governing coalition in the 16th (2005–2009), 17th (2009–2013), 18th (2013–2017) and 19th (2017–2021) Bundestags.

(*The CDU and CSU, though legally two different parties, are integral partners such that they can be de facto considered as one party, especially when coalition-building is concerned. The CSU only runs in Bavaria, which the CDU does not contest. For the purpose of our article, we shall treat the union of the two parties — CDU/CSU — as one singular party, and for convenience would simply be referred to as “CDU”.)

The SPD, which had been the CDU’s junior partner in the previous two governments (with Scholz serving as Vice-Chancellor in the 19th Bundestag), chose not to renew their ‘Grand Coalition’, so named as the two parties were, and remain, the two largest in the Bundestag. A CDU-led Grand Coalition was also formed in the 16th Bundestag as part of Merkel’s first Cabinet. The last time the SPD was in power was in the 14th and 15th Bundestags of 1998–2005, where under the leadership of Gerhard Schroder it led a governing coalition with the Greens.

This time, the SPD formed a “traffic light” coalition with the environmentalist Green Party and the libertarian Free Democratic Party (FDP) — so named because of the SPD (red), FDP (yellow) and Greens’ party colours. The FDP received 11.46% of the popular vote to secure 12.50% of the seats in the Bundestag, while the Greens received 14.75% of the votes and 16.03% of the seats. The “traffic light” coalition therefore controls 416 of the 736 seats in the Bundestag (57%).

The end of Merkel’s 16-year reign opens up a new chapter in German history, providing us with the opportunity to explore the prospects of different coalitions, and which theory best explains why the “traffic light” configuration eventually prevailed. We will do so first using academic theories on coalition-building, then matching them up with developments in real life. This will also allow us to evaluate the usefulness and limits of available theories of coalition-building.

But first, we need to understand who the players are.

1. The Parties

Seven parties won seats in the 20th Bundestag — the SPD, CDU, the Greens, the FDP, the Alternative for Germany (AfD), The Left and the South Schleswig Voters’ Association (SSW). The last-named received only one seat and represents regional interests; we can thus consider it irrelevant to coalition-building.

The six significant parties are well spread out across the political spectrum, ranging from the far left to the radical right, while also representing more specialised interests. Nonetheless, we can still position the parties relative to each other on a uni-dimensional left-right spectrum with only some complications that are easily addressed.

The CDU, as a centre-right party, is moderately conservative on both economic and social issues, while the centre-left SPD appeals more to unionised and working-class voters, and thus advocates more economically redistributive policies.

The FDP, as a libertarian party, offers an interesting case — economically it is closer to CDU, but socially (e.g. education, civil liberties) it is more aligned with the Greens and SPD; however, it should be noted that economic issues, particularly tax reform, is more salient for the FDP. Nonetheless, we could consider it to occupy a space somewhere between CDU and SPD.[1] This is obviously an oversimplification, but should still be sufficient as a rough illustration of where the parties stand relative to one another.

It is worth noting that the FDP has allied with both the SPD and CDU in the past in various governing coalitions, though its pairing with the SPD occurred mostly in the 1980s. It experienced a dip in popularity in the last decade, but was revived in the 2017 elections and made slight gains in 2021, where it was the second most popular party (after the Greens) among under-30-year-olds.

The Green Party, like the FDP, does not not represent traditional policy orientations and as such is difficult to classify on a unidimensional left-right spectrum. It emerged in the 1970s as part of the environmentalist movement, although over the decades it has attempted to link its established ecological identity to economic growth, jobs, international competitiveness and technological innovation.[2]

It should thus cause no controversy to regard the Greens as generally more progressive; further to the left than SPD but not as not more so than The Left. The Greens have never been part of a governing coalition except from 1998 to 2005 with the SPD in the 15th Bundestag.

The AfD, as one of the world’s most well-known far right political parties, has long been subject to a cordon sanitaire by the larger parties, who have largely viewed the party as unacceptable due to its extremism, including euroscepticism, anti-immigration and climate change denial.

The Left, widely considered a far-left, anti-capitalist party, has likewise been largely shunned by the larger parties; electorally it has hovered around the 10% mark since its creation in 2007.

Though a gross oversimplification to put all the parties on a uni-dimensional spectrum, for our purpose it still appears reasonable to map their relative positions from left to right. The extent to which one party is further from another is certainly up to debate, but their position vis a vis one another should be less controversial.

The Left — Greens — SPD — FDP — CDU — AfD

As already mentioned in the beginning of this article, the SPD attained  plurality of the votes and Bundestag seats while the CDU tailed narrowly behind in second place. The FDP and Greens made gains from the previous election while the AfD slid back slightly from its 12.6% of the popular vote in the previous election. Meanwhile, The Left suffered its historically worst result with just under 5% of the popular vote.

The vote and seat shares, in descending order, of the six parties are summarised in this table:

PartyVote shareNumber of seatsPercentage of seatsPolitical Orientation
Greens14.8%11815.9%Moderate left
FDP11.5%9212.5%Economic right, Social left
AfD10.3%8211.1%Far right
The Left4.9%395.0%Far left

2. Theoritical coalitions

For now, let us pretend we do not know which coalition was actually formed in December 2021. Knowing just the results of the September elections, what would the theories of coalition-building predict?

The Dutch-American political scientist Arend Lijphart has conveniently summarised, in his 2012 book Patterns of Democracy (second edition), the main theories of coalition-building, which can be classified into three categories:

Size-based minimalist theories do not take into consideration parties’ policy preferences; they are power politics at the finest — all that matters is assembling the required numbers.

The preoccupation on size and numbers, however, ignores the fact that coalitions are easier to negotiate and maintain between parties of similar policy preferences.

Policy-based minimalist theories, therefore, hypothesize the parties will want to partner with other parties that have similar political orientations, but retain the idea that only the parties minimally necessary to achieve this requirement will be part of the coalition.

Non-minimalist theories encompass coalitional abnormalities, namely minority Cabinets, which are formed by a party or coalition that possesses less than half of the seats in the legislature, and oversized Cabinets, which are coalitions with more parties than minimally required, meaning to say there are one or more ‘redundant’ parties whose departure from the coalition will not create a loss in its majority.

We shall now examine in greater detail the possible coalitions possible based on these theories.

Size-based theories

  1. Minimal size coalitions

Building on William H. Riker’s ‘size principle’ that coalitions will only involve parties that are necessary to achieve a majority in the legislature, this theory operates on the premise that parties want to maximise their participation in Cabinet. Hence, the smaller the size of the coalition in terms of the number of seats, the greater the share of ministerial appointments for each partner.

Hypothesis 1: A CDU – FDP – AfD coalition (50.3% of the seats in the Bundestag).

  • Coalitions with the fewest parties

While the previous theory is concerned only with forming a coalition with the fewest number of seats, this theory adds the prerequisite that there should first be the fewest number of parties. The reasoning is that negotiations and bargaining are easier to conduct between fewer parties. This tends to favour ‘grand coalitions’ of two large parties.

Hypothesis 2SPD – CDU “Grand Coalition” (2 parties, 54.6% of seats)

Policy-based theories

  • Minimal range coalitions

Such coalitions aim to minimise the gap between the parties at each extreme end of the coalition. The assumption is that governance is easier when parties are close together ideologically than when they are further apart.

Hypothesis 3.1: Hypothesising possible coalitions under this theory is challenging because it requires estimating the spatial distance between parties, and not just their relative positions. But it should be safe to say that the range in a coalition between the two centrist parties, the SPD and CDU, is smaller than the range in a coalition with any three parties, which by geometrical necessity we should expect to see spread out over a further distance. As such, a SPD – CDU “Grand Coalition” again appears to be the likeliest coalition under this theory.

Hypothesis 3.2: The oversized SPD – FDP – CDU is a minimal range coalition as well, given that we assume FDP is between SPD and CDU. As such, the addition of the FDP does nothing to change the range between the two most extreme ends of the coalition. This coalition is nicknamed a ‘Mickey Mouse’ or a ‘Germany’ because the colours of the three parties — red for SPD, yellow for FDP and black for CDU — match the colours of the Disney character and the German flag.

  • Minimally connected

While the previous theory is only concerned with the gap between the two extremes of a coalition, the minimally connected theory “assumes that parties will try to coalesce with their immediate neighbours and that other adjacent parties will be added until a majority coalition is formed”.[3]

Hypothesis 4.1: The oversized SPD – FDP – CDU (Mickey Mouse) coalition now definitely becomes more likely than a Grand Coalition, as the FDP is now required to “connect” the two larger parties, even though its presence in the coalition is not necessary for the formation of Cabinet.

Hypothesis 4.2: A Greens – SPD – FDP (Traffic Light) coalition would be minimally connected as well, but whether this is more likely than the “Mickey Mouse” under the minimally connected theory would depend on how one evaluates the exact spatial distance between the parties.

Non-minimal coalitions

  • Oversized Cabinet

These cabinets have more coalition partners than minimally required, meaning to say, there are one or more ‘redundant’ parties whose departure from the coalition will not lead to a loss in the coalition’s legislative majority. They usually emerge when coalition partners are unsure whether their partners will defect and thus dissolve government. The former is not the case today while the latter is unlikely given that the Cabinet can only be replaced by a constructive vote of no-confidence, making defections difficult.

Nonetheless, there are still two reasons why an oversized Cabinet is still possible in the 20th Bundestag: firstly, some policy-based coalitions are already oversized, such as the “Mickey Mouse” between the CDU, SPD and FDP.

Secondly, the addition of a smaller party to a Grand Coalition where the SPD and CDU are almost equal in size can help tilt the favour towards one side. Since oversized policy-based coalitions are oversized only by necessity and not by choice, we will focus here only on the use of oversized cabinets to gain bargaining power.

Hypothesis 5.1: A Kenya (Greens – SPD – CDU) coalition leans heavily to the left and will therefore favour the SPD, who could use the more progressive Greens as a bargaining chip against the centre-right, while keeping the CDU/CSU as a moderating influence against the Greens.

Hypothesis 5.2: For this reason, the CDU will much prefer an SPD – FDP – CDU (Mickey Mouse) coalition. However, since the FDP, as far as we are concerned, is ideologically between the SPD and CDU, such a coalition will at best be balanced and not too much in the centre-right party’s favour.

Summary of theoretically likely coalitions

NicknamePartiesType(s) of coalition
Grand CoalitionSPD CDUFewest parties (size-based)Minimal range (policy-based)
Traffic Light: green, red and yellowGreens SPD FDPMinimally connected (policy-based)
<unnamed>CDU FDP AfDMinimal size (size-based)
Kenya: green, red and blackGreens SPD CDUOversized (favouring SPD)
Mickey Mouse (a.k.a. Germany): black, yellow and redSPD FDP CDUMinimal range (policy-based)Minimally connected (policy-based)Oversized (favouring CDU)
Jamaica: green, yellow and blackGreens FDP CDUDoes not fit with any of the mentioned types of coalitions.

3. Measuring up against reality

Theoretically there appears to be at least five possible coalitions, among which the oversized “Mickey Mouse” appears most likely (satisfying three coalition theories) followed by the Grand Coalition appears the most likely (satisfying two theories).

But we know that it was the “Traffic Light” coalition (SPD, Greens, FDP) that eventually succeeded. Why so?

Firstly, in an electoral system like Germany’s with strong programmatic party competition, a rather clear ideological spectrum, and diverse (but not excessively factionalised) interests across the country, parties’ policy positions matter a great deal. Size-based theories are entirely about power and emerged from game-theory analysis[4]. This makes them ill-suited to predict coalitions where policy commitments have to be upheld.

Secondly, the particularities of this election is such that the grand coalition between the SPD and CDU was largely out of the question, as both parties have rejected continued partnership. Consequently, since the oversized Mickey Mouse and Kenya coalitions involve both the SPD and CDU working together (albeit with a third party), they appear unlikely as well.

Furthermore, the two coalitions that involve the AfD can be ruled out, given the party’s extreme position.

The Jamaica coalition between the Greens, FDP and CDU — heretofore unmentioned — also appears unlikely given the rather incompatible ideological positions of the progressive, libertarian and centre-right parties. The Greens will certainly prefer the SPD over CDU, while the FDP are known to be flexible.[5]

This leaves only the Traffic Light (Greens – SPD – FDP) coalition with a serious chance at success, and as recent reports indicate, is now all but certain.[6] It would be, in this round of coalition-building, both a minimal range and minimally connected coalition and completely policy-based. It is incompatible with size-based coalition possibilities as there are plenty more minimalist alternatives.


The “Traffic Light” coalition governing the 20th Bundestag, as it turns out, is the first time since the 3rd Bundestag of 1957–61 that a Cabinet has more than two parties.

This reflects a decades-long trend of the shrinking influence of the two major parties. In the 1980s and 1990s, the rise of the Greens — and to some extent The Left after the reunification of Germany — divided the left-wing camp.[7] In the previous decade, the eurozone and refugee crises, accompanied by the rightward shift of the AfD, pulled voters away from the CDU. The 20-odd percent of votes that the CDU and SPD each won in this election is a far cry from the 35 to 40-odd percent that they achieved before the 1990s.

The trend is here to stay. The Greens and the FDP are popular among the young, together winning 44% of first-time voters in this election.[8] We can thus expect to see a more level playing field in the future where no party or parties thoroughly dominate the electoral scene. Any tri-party coalition will present interesting dynamics for future governance. More parties means more interests to accommodate. This may pose challenges to governance and even paralysis, but also possibly opportunities as the coalition partners have to compromise and find strength in diversity. A problem with grand coalitions, theoretically, is that it does not give voters much room to “vote out” the incumbent. This may not have been an issue for Germany for the last 16 years under the steady hand of Angela Merkel, but as it enters a new era, greater competition is very likely to be the norm.


Brakel, Alexander (2021). On the Brink of a Post-Merkel Germany: Understanding the 2021 Federal Elections, Israel Journal of Foreign Affairs, DOI: 10.1080/23739770.2021.1964053.

Deutsche Welle. “What Does the AFD Stand for?” DW.COM. Accessed February 19, 2022.

Hancock, M. Donald. Politics in Europe: An Introduction to the Politics of the United Kingdom, France, Germany, Italy, Sweden, Russia, Poland, and the European Union. Washington, D.C.: CQ, 2011.

Lee Ann Banaszak, Peter Doerschler, Coalition type and voter support for parties: Grand coalitions in German elections, Electoral Studies, Volume 31, Issue 1, 2012, Pages 46-59, ISSN 0261-3794,

Lijphart, Arend. Patterns of Democracy Government Forms and Performance in Thirty-Six Countries. New Haven, CT: Yale University Press, 2012.

[1] Hancock, pp. 265

[2] Hancock, pp. 268

[3] Lijphart 2012, pp. 84.

[4] Riker, The Theory of Political Coalitions.

[5] Allen 2021.


[7] Politics in Europe, 6th ed.; Brakel 2021

[8] Allen 2021

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