Has the Overton Window Shifted in the Dutch Parliament?

A data-driven analysis of 2,986 right-wing motions (2016–2026) reveals a surprising answer: the window didn't shift. The right-wing moved toward it.

Analysis based on 2,986 classified right-wing motions, 2,869 two-dimensional extremity scores, MP-level voting records across 33 quarters, and 200 systematically classified policy mechanisms.

The Question

After the PVV's historic election victory in November 2023 and the formation of the Schoof cabinet in July 2024, a question dominated Dutch political commentary: has the Overton window shifted to the right? Have centrist parties (VVD, D66, CDA, NSC, ChristenUnie, BBB) become more accepting of right-wing policy positions?

We analyzed every right-wing motion submitted to the Dutch Tweede Kamer between 2016 and 2026 — 2,986 motions classified by keyword matching and voting patterns, scored on two dimensions (rhetorical extremity and material policy impact), and tracked across 33 quarters of parliamentary activity.

The answer is more nuanced — and more interesting — than a simple yes or no.

Three Indicators at a Glance

Centrist support surged. But the motions themselves became less materially impactful — the share of high-impact proposals (M≥4) dropped from 23.7% to 11.3%. The Overton window did not shift rightward. Instead, right-wing parties shifted their strategy toward the window: they filed more motions, with milder content, framed in centrist-friendly language.

Indicator 1: How Centrists Voted

The cleanest signal is in how centrist parties voted on right-wing motions. Using a strict centrist definition (VVD, D66, CDA, NSC, BBB, CU), average support rose from 0.251 pre-2024 to 0.507 post-2024 — a Cohen's d of +0.65.

Not a Coalition Effect

After the Schoof cabinet formed, PVV entered government, which could mechanically inflate support for its own motions. So we restricted to opposition-only right-wing motions. The effect is larger: d = +0.85, with support jumping from 0.270 to 0.543. Coalition dynamics slightly suppressed the observable shift.

The Gradient Persists

Centrists still differentiate by how radical a motion is — high-extremity motions (buckets 3–5) gained proportionally more support than mild motions (buckets 1–2). This is consistent with genuine tolerance expansion, not a compositional shift toward milder motions.

Who Drove the Shift?

The shift is not uniform across centrist parties:

The two Christian-conservative parties — CDA and ChristenUnie — more than doubled their migration vote share. D66 barely moved. The shift is not "centrists accepting right-wing content" — it is the Christian-conservative wing of the center moved substantially, while the progressive wing barely budged.

Indicator 2: Spatial Divergence

If centrists are voting more with right-wing motions, one might expect ideological convergence — centrist parties drifting rightward. Procrustes-aligned SVD analysis shows the opposite.

Centrist parties moved left on both SVD axes — more welfare-oriented economically, more cosmopolitan culturally. Right-wing parties moved further into the nationalist corner. The cultural distance between the two groups widened from 0.282 to 0.428.

This is spatial divergence, not convergence. The puzzle: how can centrists vote more with right-wing motions while moving further away from them ideologically?

Indicator 3: Content Extremity — The 2D Story

The original single-dimensional extremity score showed no increase post-2024 (d = −0.09). But a single score conflates two independent dimensions:

• Stylistic extremity — how inflammatory is the language?
• Material impact — how consequential is the proposed policy?

These two dimensions are only moderately correlated (r = 0.47). And their trajectories diverge:

Right-wing motions became more restrained in language while simultaneously becoming less materially consequential. This is holistic moderation — both the packaging and the content shifted toward the center.

The Gravity Question: Do Meaningful Motions Show the Same Pattern?

Not all motions are equal. A symbolic declaration ("we express concern about X") is fundamentally different from a bill that restricts asylum seekers' rights. Does the centrist support shift hold when we filter to only substantive, high-impact motions?

The shift is real across ALL gravity levels, including motions that touch fundamental rights. If anything, the effect is slightly larger for high-impact motions (+0.263) than for the full dataset (+0.255). This is not a story about centrists rubber-stamping symbolic gestures — it's a story about genuine accommodation of substantive right-wing policy proposals.

The Left-Wing Control: Are Centrists Drifting Left or Right?

A key concern: the SVD shows centrists moving left. Could this mean they're simply voting more with everyone — including left-wing parties — rather than specifically accommodating the right?

We compared centrist voting on motions submitted by left-wing parties (SP, GroenLinks-PvdA, PvdD, Volt, DENK) versus right-wing parties (PVV, FVD, JA21, SGP):

The centrist support surge is entirely concentrated in right-wing motions. Centrist support for left-wing motions didn't change at all. The SVD's leftward drift is not driven by symbolic left-wing cooperation — it's driven by centrists voting more with right-wing parties on right-wing proposals while maintaining their existing voting patterns on everything else.

Who Filed the Motions? JA21 as the Primary Driver

Treating right-wing parties as a bloc obscures a critical finding. Breaking down by party:

JA21 drives the moderation effect — they are the only party that both significantly increased motion volume and centrist support simultaneously. PVV's +0.125 shift starts from a very low baseline and coincides with entering government (fewer, less radical motions). SGP was already a "mainstream" right-wing party pre-2024. FVD remains firmly marginalized.

How Did They Do It? Mechanism Classification

A systematic classification of 200 motions across 10 mechanism types reveals the dominant pathways through which right-wing motions gain centrist support:

Post-2024 High-Support Motions (CS > 0.5)

The contrast with low-support motions is sharp. Zero system-dismantling proposals (asylum stops, treaty exits, fundamental institutional upheaval) achieved high centrist support post-2024. The truly ideological right-wing agenda does not gain centrist support.

Consensus framing — appealing to shared values like safety, efficiency, and pragmatism — is significantly more common in high-support motions (24%) than low-support ones (8%): χ² = 6.0, p = 0.014.

When Did It Happen? The Temporal Trajectory

Quarterly analysis across 33 quarters (2016-Q2 through 2026-Q1) reveals the exact timing:

The trajectory resembles an electoral response function — a rapid jump after the election, a peak during the honeymoon phase, and a gradual decline. The shift may be an electoral-cycle phenomenon rather than a permanent Overton window movement.

The Voting Margin: A Better Metric Than Pass Rate

Dutch parliament passes 96%+ of all motions. This makes pass rate a useless metric — it cannot register a shift of any magnitude. We computed a continuous alternative:

margin = (voor − tegen) / (voor + tegen + afwezig)

Voting margin detects temporal patterns at a granularity pass rate cannot. The pre-2024 margin was negative (right-wing motions lost by 8 points on average). Post-2024, they won by 13 points. The shift from losing to winning is the real signal — not the binary pass/fail.

Can We Predict Which Motions Succeed?

A predictive model (logistic regression, AUC-ROC = 0.81) identifies the strongest predictors of centrist support:

Who submits matters more than what the motion says. FVD motions systematically receive low centrist support regardless of content. SGP and JA21 motions do better. Higher rhetorical extremity and material impact both predict lower centrist support — centrist parties respond more to policy substance than to framing.

What This Means

The Dutch political landscape post-2024 is not best described as "the Overton window shifted right." A more accurate description:

1. Right-wing parties strategically moderated. They filed more motions, with milder content, framed in centrist-friendly language. The share of high-impact proposals (M≥4) dropped from 23.7% to 11.3%.
2. Centrist parties rewarded the moderation. Support surged from 0.251 to 0.507, driven primarily by CDA and ChristenUnie on migration issues.
3. The ideological divide held or widened. SVD spatial analysis shows centrists moved left on both axes while right-wing parties moved further right. The cultural gap widened by +0.146.
4. The effect may be temporary. Quarterly data shows centrist support peaked in 2024-Q4 (0.648) and has since reverted to 0.334 — below the pre-shift threshold.
5. Migration is the exception. The one domain where genuine acceptance expansion (not just content moderation) is measurable. Centrists went from never supporting M=5 migration motions to backing nearly 1 in 5.

Methodology

This analysis uses data from the Dutch Tweede Kamer OData API, covering 2,986 classified right-wing motions (2016–2026). Key methodological choices:

• Centrist definition: Strict: D66, CDA, ChristenUnie, NSC (not VVD or BBB).
• Extremity scoring: Two-dimensional (stylistic extremity + material impact), scored by LLM with manual validation (75% agreement). 2,869 motions scored (96% of total).
• SVD alignment: Procrustes-aligned PCA with flip correction ensuring right-wing parties appear on the right.
• Mechanism classification: 200 motions classified by LLM, validated with inter-rater reliability (Cohen's κ = 0.41).
• Statistical approach: Descriptive (Cohen's d) rather than inferential. Small-N time series (8 pre-2024 annual windows, 3 post-2024) limits the power of formal statistical tests.