legislation_cosponsors: 113-sres-539, T000464

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
113-sres-539	T000464	Sen. Tester, Jon [D-MT]	D	MT	2014-09-09	1