The FULL rating is upheld. Merkley did exactly what he promised — cosponsor and support Bernie Sanders' single-payer Medicare for All legislation. Three of the four cited sources were fetched and directly confirm the outcome and the quoted text: (1) Merkley's own Senate office release (2017-09-11) announces his cosponsorship and contains verbatim the quote "It's time to simplify health care and lower patients' costs, and embrace Medicare for All."; (2) OPB's headline matches exactly ("Jeff Merkley Co-Sponsors Bernie Sanders' 'Medicare For All' Legislation," 2017-09-11); (3) the Sanders Senate release lists Merkley among "all original cosponsors, including ... Jeff Merkley (D-Ore.)" for the Medicare for All Act of 2022, confirming sustained support across sessions. The fourth source, the Congress.gov S.1804 cosponsor record, could not be fetched (HTTP 403 — Congress.gov and its GovTrack mirror block automated retrieval), but its specific claim (Merkley as an original cosponsor with a 09/13/2017 cosponsor date) was independently corroborated via web search, which surfaced the bill's introduced text listing "Mr. Merkley" among the original cosponsors on the 2017-09-13 introduction. FULL (not CHAMPIONED) is appropriate because Sanders authored and led the bill; Merkley was one of roughly sixteen original cosponsors fulfilling the promised action. The outcome does not overstate the evidence — the promise was to cosponsor and support, which is documented, and the rationale correctly acknowledges the bill never received a floor vote.