Maine regulators have rejected a Lewiston-based health insurance cooperative’s request to alter its 2018 plan under the Affordable Care Act, a move the insurer made in response to competitors.

The Maine Bureau of Insurance on Wednesday rejected the request from Maine Community Health Options to make changes to the individual silver-level plans it will offer Mainers in the online marketplace set up by the federal health care law.

The Portland Press Herald reported the co-op took issue with a proposal from Anthem Blue Cross Blue Shield, which Community Health Options CEO Kevin Lewis called “a bronze-level plan that is masquerading as a silver-level plan.”

Both insurers have proposed rate increase of about 20 percent.

[Obamacare premiums are about to get more expensive in Maine]

The Affordable Care Act rates plans as bronze, silver, gold or platinum, depending on the level of coverage.

Lewis said the Blue Shield threatens to lure away customers just as the cooperative has recovered from two years amassing an operating deficit of $90 million. In the first quarter of the year, the cooperative had a $3.7 million surplus, after working with regulators to regain its financial footing.

In its order denying MCHO’s request to tweak its silver plans, regulators said they had to stick by a hard deadline of July 14 for any changes. The request from MCHO came in on July 21, arguing that Blue Cross’ plan created an outlier that resulted in “distorted rating plans.”

The bureau noted that regulators will review the plans for compliance with the health care law and federal officials will conduct their own review to determine if the proposed 2018 individual rates contain outliers that stand to distort the market.