Maine’s campaign finance watchdog agency voted unanimously Friday to continue efforts to determine whether a limited liability corporation working to block a controversial transmission line project should have registered as a political action committee or a ballot question committee.

In a 5-0 vote, the Commission on Governmental Ethics and Election Practices also agreed to pursue a subpoena for financial information from an unidentified Virginia political consultant who has worked with the LLC, Stop the Corridor, to stop the New England Clean Energy Connect project.

The project will be the subject of a statewide ballot question in November.

After a nearly 3-hour video conference that was closed to the public, the commission voted to deny a request to vacate its administrative subpoena for financial records. The commission is trying to determine what role Stop the Corridor and the consultant are playing in the ongoing political battle over the 145-mile transmission line project being built by Central Maine Power and Hydro-Quebec in western Maine.

The $1 billion project would serve as a conduit, bringing up to 1,200 megawatts of Canadian hydropower to Massachusetts.

The commission voted to delay until next Friday a decision on whether it would continue to pursue a separate subpoena of Stop the Corridor’s records, as the commission staff continues negotiations with an attorney representing the LLC about what it should be required to disclose.

But the commission also appears to be girding for a court battle with the unnamed consultant, whose identity is being shield by the commission under state laws that protect sensitive financial and political information.

During the brief public portion of the commission’s meeting Friday, executive director Jonathan Wayne suggested the commission give the parties two weeks to comply with the request for information, but also said he didn’t expect them to.

“If I thought there was a chance that the client was actually going to comply with the subpoena I would suggest a longer time period, but it seems to me we are heading towards court,” Wayne said.

The commission’s staff recommended it investigate following a January 2020 complaint by Clean Energy Matters, a political action committee that is being bankrolled by project supporters, mainly CMP and its parent company Avangrid, a subsidiary of the Spanish power giant Iberdrola. That complaint, filed by Newell Augur, an attorney for Clean Energy Matters, notes that Stop the Corridor has worked in concert with No CMP Corridor, which is a registered PAC.

But attorneys for Stop the Corridor have argued their client is not a PAC, as it was not formed for the primary purpose of supporting or defeating a ballot question and has only provided in-kind donations to No CMP Corridor.

A letter to the commission from Stop the Corridor attorney Kate Knox states the LLC was formed in April 2018 out of concern the corridor would “result in catastrophic environmental and economic damage” to the state of Maine. Knox notes the primary purposes of Stop the Corridor, like that of other organizations working to defeat the transmission line project, is to engage in the permitting process for the corridor at the various levels of local, state and federal government.

But in his letter to the commission, Augur argues that Stop the Corridor has engaged in political activity of its own, purchasing in excess of $1.4 million in television advertising in 2020 alone. It also contributed $50,000 of in-kind donations, including postage, printing costs, office supplies and website development to No CMP Corridor, and donated $40,000 of “staff time for volunteer recruitment.”

“This is disturbingly consistent with a lack of transparency of unreported dark money that has already been spent by out-of-state fossil fuel interests opposed to the clean energy transmission line,” Augur writes.

Combined, the political spending by the opposing sides of the power line debate has toppled all state records for a ballot question campaign. According to campaign finance records, Clean Energy Matters has already spent $19.5 million in an effort to bolster public support for the corridor expansion, which is meant to deliver electricity from Quebec to Massachusetts via Maine. No CMP Corridor has spent $165,000 to defeat the corridor or counter the messaging from CMP and its partners, campaign finance records show.

In November, state voters will be asked if the Legislature should be required to approve any power transmission project over 50 miles long. But that question may well be moot as construction of the corridor is already well underway and much of the line could be completed before any new law could go on the books.

In 2019, Gov. Janet Mills threw her support behind the project after negotiating a package of benefits to the state, worth about $258 million over 40 years, that are designed to lower electric bills, advance clean-energy efforts and fund other public projects.

Opponents previously collected more than 63,000 signatures for a “people’s veto” referendum of the power corridor, but the Maine Supreme Judicial Court ruled the question was unconstitutional because approval of the expansion was made by the Public Utilities Commission. The court ruled a people’s veto referendum can only be used to nullify legislative actions, not regulatory decisions by state agencies.

Correction: This story was updated at 12 p.m. Monday, June 14, 2021 to correct the spelling of Newell Augur’s name.