Adversarial re-check: I independently re-verified the underlying record against U.S. GPO GovInfo BILLSTATUS bulk data (primary, machine-readable, not the prior researcher's citations) for all four Congresses claimed. Every claim held. (1) H.R.1384, Medicare for All Act of 2019 (116th, sponsor Rep. Jayapal): Rep. Schiff, Adam B. cosponsor 2019-02-27, isOriginalCosponsor True. (2) H.R.1976, Medicare for All Act of 2021 (117th, sponsor Jayapal): Schiff cosponsor 2021-03-17, isOriginalCosponsor True; latest action was referral to subcommittee - no floor vote, no chamber passage. (3) H.R.3421, Medicare for All Act (118th, sponsor Jayapal): Schiff cosponsor 2023-05-17, isOriginalCosponsor True. (4) S.1506, Medicare for All Act (119th, sponsor Sen. Sanders): Sen. Schiff, Adam B. [D-CA] cosponsor 2025-04-29, isOriginalCosponsor Yes - one of only 15 original cosponsors out of 47 Senate Democrats (total cosponsors have since grown to 17 with Van Hollen 2025-11-18 and Smith 2025-12-02). The prior rating's congress.gov URLs are real canonical pages (they return 403 to automated fetchers because congress.gov blocks bots, not because they are broken or invented); the substance of every quoted line was reproduced independently from GovInfo. Standard-consistency check: the bill has never received a floor vote in either chamber, so no vote was available to take; original cosponsorship at introduction, repeated across four consecutive Congresses and carried across a chamber change, is a sustained affirmative act of sponsorship well beyond 'a single supporting vote,' which is exactly the line the rubric draws for CHAMPIONED. I would apply the same label to a member of the opposing party who was an original cosponsor of that party's flagship bill in four straight Congresses. It falls short of FULL (never enacted) and short of the strongest CHAMPIONED case because he is not the lead sponsor (Jayapal/Sanders) and I found no verified evidence of him driving the effort - floor leadership, whip work, or forced votes - beyond repeat cosponsorship. One unverified counter-signal: a January 2024 OC Register report of a California Senate debate was summarized in search results as Schiff backing an 'opt-in' Medicare for All framing, which is softer than single payer; I could not retrieve the article to confirm the verbatim quote, so I do not treat it as established, and in any case his April 2025 original cosponsorship of the actual single-payer bill post-dates it. Confidence held at 0.72 for the leadership gap, not for any doubt about the record.