The Maine Public Utilities Commission is allowing the $2.6 billion sale of Central Maine Power Company to move forward without a state review.

Regulators voted 2-1 Tuesday to waive a review of the deal in which Spanish energy giant Iberdrola will acquire the remaining 18% of CMP’s parent company that it does not currently own.

The utility contends the Commission had already authorized Iberdrola’s indirect ownership of CMP and Maine Natural Gas in 2008 when Iberdrola acquired a predecessor of Avangrid.

Opponents, including Public Advocate William Harwood and consumer groups say the deal transforms the publicly traded Avangrid into a private company and exempts it from filing certain financial records with the Securities and Exchange Commission.

The sale is still under review in Connecticut and New York where Avangrid also operates.

CMP is Maine’s largest electricity provider, serving about 635,000 businesses and households in the southern and central part of the state.