A political action committee bankrolled by two Texas energy companies was fined $2,500 on Monday by the Maine Ethics Commission for violating state campaign finance law.

The commission voted 5-0 to impose the penalty against Mainers for Local Power, which failed to notify one of its major contributors – the Texas energy company Calpine – that the company was required to file a major contributor report with the commission because it had donated more than $100,000 to the PAC.

Mainers for Local Power was formed by Calpine and Vistra Energy to oppose the New England Clean Energy Corridor and support a ballot question going to voters in November aimed at killing the project.

The $2,500 penalty is the same amount as one imposed in March on Clean Energy Matters, a PAC supporting the 145-mile transmission line project, which would carry hydropower from Quebec to the New England power grid to serve utility customers in Massachusetts.

The dueling sides in the battle over the more than $1 billion project have poured record levels of money into their respective campaigns as they try to sway public opinion on the project, which is being built by a company that’s a partnership between Central Maine Power Co. and Hydro-Quebec.

Campaign finance records show Clean Energy Matters has spent $10.3 million in 2021 and a total of $25.2 million since forming. The PAC’s top contributor is NECEC Transmission LLC – the partnership company – which has donated $10.77 million, while CMP’s parent company Avangrid Service Co. has donated $8.7 million and CMP has donated $7.4 million.

Mainers for Local Power has spent $3.3 million in 2021 and a total of $6 million since forming in 2019. The PAC’s top contributors include NextEra Energy Resources, which has contributed $6.5 million to the PAC. Calpine has donated $688,823 and Vistra Energy Corp. has donated $666,323.

In November, voters will consider a ballot question aimed at blocking the project that includes a retroactive requirement that leases of public lands for energy transmission projects must be approved by a two-thirds vote of the Maine Legislature. The corridor crosses public lands, for which leases have been issued.

Superior Court Justice Michaela Murphy recently vacated a lease of public lands for a 1-mile section of the corridor, a ruling that could also imperil the project.

Murphy said in her ruling this month that the lease is no longer valid because state public land officials failed to conclude that the lease would result in no reduction or substantial alteration to the public lands being leased.

The penalty issued Monday is the second under a new law requiring those donating more than $100,000 to a political action committee to disclose their top five contributors, the other being Clean Energy Matters.