AUGUSTA, Maine (AP) Democratic Gov. Janet Mills asked tribal chiefs and legislatives leaders in a letter made public Monday to drop their effort to amend a 1980 land settlement deal that gave the state of Maine some governmental power over tribes.

Mills said the proposal to expand tribal sovereignty could be a setback in tribal relations with her administration, instead of building on recent successes.

“I do not wish to have a confrontation,” she wrote in the letter. “It would serve no constructive purpose and only inflame emotions on all sides of the discussion.” The letter was written Thursday night, the day before the bill failed to advance in the appropriations committee.

Maggie Dana, chief of the Passamaquoddy Tribe at Pleasant Point, said previously she hoped the governor would be “on the right side of history” and agree to the changes long sought by tribes in the state.

For the tribes, it has been a long, frustrating battle since they traded some rights to the state under the $81.5 million Maine Indian Land Claims Settlement Act of 1980, signed by President Jimmy Carter.

Because of the settlement, tribes in Maine have less autonomy than tribes elsewhere across the country, and their reservations are treated like municipalities, subject to state law.

Critics of extending tribal sovereignty, including the governor, feared there could be unintended consequences and further litigation if the relationship between the state and tribes changed.

Lawmakers earlier approved — and the governor signed — a bill that gives the Passamaquoddy Tribe at Pleasant Point the right to regulate its own drinking water, partnering with the U.S. Environmental Protection Agency, instead of state regulators.

The Legislature also was poised to send to the governor a proposal to provide mobile sports betting revenue to the tribes.