How do some bills advance while others stall? This paper explores how interest groups influence the legislative process through their endorsements in Dear Colleague letters.

These letters serve as key information sources for congressional members, especially early on. We find that strong endorsements from well-connected groups act as powerful cues to sway member opinions and attract initial cosponsors.

As legislation progresses, these influential groups have less direct impact. Instead, broader coalitions of organizations combined with growing numbers of cosponsors significantly boost a bill's chances of passage.

💡 Key Findings:

• Well-connected groups' early endorsements act as strong cues for members.
• Broader support (more co-sponsors and endorsing orgs) increases likelihood of success later on.

🔍 Real-World Relevance:

This research demonstrates how interest group political signaling shapes U.S. public policy via cue-taking mechanisms.