A common belief is that open primaries reduce political extremism by electing moderates.

Data & Methods

We analyze a unique dataset combining state legislator ideal points with detailed primary system information across U.S. states.

Key Findings

• Open primaries have minimal impact on the ideology of elected officials.
• The effect of nomination systems on producing moderate politicians is negligible.
• Legislators' ideological leanings remain largely unaffected by whether voters include nonparty members in primaries.

Why It Matters

This suggests primary system reforms may not effectively address polarization concerns, prompting a rethink about other strategies for achieving more centrist representation.