legislation_cosponsors: 119-sres-564, M000133

Cosponsors for tracked legislation. Distinguishes original cosponsors (signed on at introduction) from later additions. Linked to congress_members via bioguide_id.

This data as json

bill_id	bioguide_id	full_name	party	state	sponsorship_date	is_original_cosponsor
119-sres-564	M000133	Sen. Markey, Edward J. [D-MA]	D	MA	2025-12-17	1