Former Interior solicitor William Doffermyre registers to lobby for Gillon Capital on Cuban mining acquisition

By Sofia Linwood

WASHINGTON — William Doffermyre, who served as solicitor of the Interior Department until May, has registered as a lobbyist for Gillon Capital, a Texas investment fund seeking to acquire a controlling stake in the Cuban nickel and cobalt operations of Canada’s Sherritt International, according to Lobbying Disclosure Act filings posted Oct. 20.

The registration, filed by Doffermyre’s Dallas firm, Judgment Premium Advisors, describes the work as “seeking licenses, waivers and other policy and/or funding support relating to a potential acquisition of a foreign company that mines critical minerals in Cuba.” It lists foreign relations, fuel and natural resources as issue areas.

The proposed deal follows President Trump’s May 1 executive order imposing sanctions tied to Cuba. A White House fact sheet said the order was “imposing new sanctions on the Cuban regime, protecting U.S. national security,” and that the president “is addressing the national security threats posed by the communist Cuban regime by taking decisive action to hold the Cuban regime, and those that perpetuate it, accountable.” The Treasury Department’s Office of Foreign Assets Control published related actions the same day.

When Doffermyre left the department, an Interior spokesperson told E&E News that he “is a dedicated public servant who took time away from family to serve in the Trump administration,” adding: “We are grateful for his service to our great nation and wish him all the best as he rejoins the private sector and spends more time with his family in Texas.”

The filings

The registration lists Doffermyre as the sole lobbyist and discloses his covered positions as solicitor of the Interior Department, senior adviser in the White House Office and vice president and general counsel of the Overseas Private Investment Corporation. Doffermyre joined the administration in February 2025 and was confirmed as solicitor in September 2025, E&E News reported; his nomination statement to the Senate Energy and Natural Resources Committee describes his background.

The firm filed quarterly reports the same day. The second-quarter report lists $40,000 in income and contacts with the Treasury Department and the Executive Office of the President. The third-quarter report lists $150,000 and contacts with the Defense Department, the Export-Import Bank, Treasury and the Executive Office of the President. The firm also filed an amendment to its registration. The registration lists an effective date of July 1.

The Sherritt deal

Sherritt said Oct. 20 that OFAC had issued a specific license allowing fuel, fuel oil and sulfur to be supplied to the Moa Nickel operations in Cuba. The company called it the first of a series of emergency licenses needed to restart operations and for Gillon Capital to acquire a controlling interest, and said the license requests were prepared “in close coordination with Gillon Capital.” Sherritt said the two sides signed a non-binding term sheet dated May 19 and that it had reached an interim consent agreement on Sept. 23 with Moa Bay Mining Co., which holds a certified claim under Title III of the Helms-Burton Act.

Sherritt said it suspended direct participation in its Cuban operations on May 7, after the executive order, and halted refining at its Fort Saskatchewan, Alberta, plant on June 22. It has disclosed material uncertainty about its ability to continue as a going concern and said it expects a first shipment in the fourth quarter.

The Miami Herald reported in August that Gillon is tied to Ray Washburne, a Texas businessman who led OPIC during Trump’s first term, and that a rival U.S.-led consortium had also made an offer for Sherritt. The Herald reported that the State Department had not objected to the negotiations, according to both bidders.

The Inquisitor is seeking comment from Doffermyre, Gillon Capital, Sherritt, the Interior Department and the Treasury Department.

Photo: The entrance to the Stewart Lee Udall Department of the Interior Building in Washington, Feb. 10, 2025. G. Edward Johnson (CC BY 4.0), via Wikimedia Commons.