Who Makes the Cut? The Impact of Small Parties on Germany’s Coalition Options
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Published 12 February 2025
Key findings
Small parties decide coalitions – FDP, Die Linke, and BSW's entry shifts coalition viability.
The FDP missing out is the most likely, boosting the Grand Coalition's chances.
BSW and Die Linke compete for the same voters—gains for one reduce the other's chances of crossing the 5% threshold.
1. Why this matters
The upcoming election is all but certain to yield a fragmented Bundestag, with no outright majority. While the centrist CDU, SPD, and Greens will still hold over 50% of seats combined, coalition-building hinges on whether any or all of the FDP, Die Linke, and BSW—each polling near the 5% threshold—make it into parliament. Die Linke has an advantage in that it has a secondary path into the Bundestag by winning three direct mandates across their targeted seats.
To capture the uncertainty surrounding coalition possibilities, we simulate multiple election outcomes based on recent polling data and voter flows to estimate both the central seat distributions and the probability of different coalitions forming under varying small-party entry scenarios.
By considering all eight possible combinations of these parties entering or failing to enter parliament—of which we present the four most likely ones plus the "no small party enters" scenario—our simulations determine which coalitions are mathematically possible or impossible and assign probabilities to their viability under different scenarios.
2. Small Party Entry Scenarios
Scenario 1 - Die Linke, BSW & FDP Enter
A highly fragmented Bundestag emerges in this scenario, where all three smaller parties clear the threshold, reducing the seat shares of larger parties. This weakens the CDU/CSU’s ability to form a Black-Green coalition and boosts the likelihood of a Kenya, Germany or Jamaica coalition.
Coalition Scenarios:
(probability of coalition getting >315 Bundestag seats)
The Kenya coalition (CDU/CSU, SPD, Greens) (99%)
Germany coalition (CDU/CSU/SPD/FDP) (96%)
Jamaica coalition (CDU/CSU/Greens/FDP) (70%)
CDU/CSU/AfD (70%)
Grand coalition (CDU/CSU/SPD) (13%)
Black-Green (CDU/CSU/Greens) (4%)
Scenario 2: Die Linke & BSW Enter
In about 33% of simulations, the FDP misses the threshold while both BSW and Die Linke make it in—driven partly by Die Linke’s recent uptick in polling (and their chance at direct mandates). This combination emerges as the single most common outcome in our simulations. Under this scenario, the probability that a Grand Coalition between the SPD and CDU becomes feasible lies at 40%, while Black-Green becomes highly unlikely at 16%, reflecting the competition for votes on the centre-left to left side of the political spectrum, where BSW and Die Linke’s gains come partly at the Greens’ expense.
Coalition Scenarios:
(probability of coalition getting >315 Bundestag seats)
The Kenya coalition (CDU/CSU, SPD, Greens) (99%)
CDU/CSU, AfD (99%)
Grand Coalition (CDU/CSU, SPD) (40%)
Black-Green (CDU/CSU, Greens) (16%)
Scenario 3: Die Linke Enters
With both FDP and BSW failing to cross the threshold, the coalition landscape shifts significantly in favour of traditional alliances. The CDU/CSU and SPD benefit the most, making a Grand Coalition much more likely, while Black-Green also gains viability.
Coalition Scenarios:
(probability of coalition getting >315 Bundestag seats)
The Kenya coalition (CDU/CSU, SPD, Greens) (99%)
CDU/CSU, AfD (99%)
Grand Coalition (CDU/CSU, SPD) (94%)
Black-Green (CDU/CSU, Greens) (59%)
Scenario 4: BSW Enters
With both FDP and Die Linke missing the threshold, Black-Green becomes more viable than in other scenarios, benefiting from a clearer parliamentary arithmetic. Meanwhile, the Grand Coalition remains a stable fallback option.
Coalition Scenarios:
(probability of coalition getting >315 Bundestag seats)
The Kenya coalition (CDU/CSU, SPD, Greens) (99%)
CDU/CSU, AfD (99%)
Grand coalition (CDU/CSU, SPD) (86%)
Black-Green (CDU/CSU, Greens) (63%)
Scenario 5: No Small Party Enters
With all small parties failing to cross the threshold, the coalition landscape simplifies significantly, favouring established alliances. Under this scenario, both Black-Green and the Grand Coalition look stable.
Coalition Scenarios:
(probability of coalition getting >315 Bundestag seats)
The Kenya coalition (CDU/CSU, SPD, Greens) (99%)
CDU/CSU, AfD (99%)
Grand coalition (CDU/CSU, SPD) (99%)
Black-Green (CDU/CSU, Greens) (77%)
3. Simulated Seat Distributions in the Bundestag
The following charts show implied seat distribution per party across all our simulations. With 316 seats required for an outright majority, no simulation results in a single party achieving this threshold.
4. Background/Method
We start by blending a weighted average of public polls (to get each party’s baseline support) with a competition measure derived from net voter flows, estimated from weighted polling data, that estimates how votes shifted between parties between the 2021 federal election in Germany and today. This competition is used to set negative correlations—if one party gains, others with high net flow from that party are likely to lose. We then sample from a multivariate normal distribution that respects both the poll-based averages and these negative correlations, producing realistic simulations where parties compete for the same voters in each run. In a second step we separately simulate Die Linke’s probability of winning three direct mandates (thus entering the Bundestag even below the five percent threshold) and assume the SSW receives one guaranteed seat.