The promise (made 2023-02-07) was to file a federal amicus brief supporting the Willow oil project in the litigation challenging its approval. All three cited sources are reachable and document that Sullivan did exactly this AND led the effort, clearing the CHAMPIONED leadership bar. Sullivan's own Senate press release states verbatim: "In September, Sen. Sullivan led an amicus brief with his Alaska congressional delegation colleagues to the court in support of Willow," and "The federal judge referenced arguments presented in the amicus in her decision today." Murkowski's release confirms verbatim: "On March 24, the Alaska congressional delegation submitted an amicus brief in the case that was joined by both bodies of the Alaska Legislature," and additionally quotes Sullivan describing "the congressional amicus brief, which I was honored to lead." The ADN secondary source confirms the delegation and Legislature filed a brief backing Willow, with Sullivan quoted verbatim on the brief laying out "what we see as the public interest, which is to deny this preliminary injunction." This is an active legal filing Sullivan is credited with leading/authoring in primary sourcing (not merely a vote or generic support), so CHAMPIONED is appropriate. Confidence slightly below certainty only because it was a co-led joint delegation brief (Murkowski is likewise credited with leading it), but the underlying fact that Sullivan filed and drove the amicus brief is firmly established across primary sources.