Press Herald graphic by Michael Fisher

The Maine Public Utilities Commission is set to vote Thursday morning on whether to issue a key permit needed by Central Maine Power to build a controversial transmission line through western Maine.

The 9 a.m. deliberations, at the PUC offices in Hallowell, will mark a milestone in CMP’s quest to gain regulatory approvals for its 145-mile line meant to to carry Canadian hydro power to Massachusetts.

On March 29, the PUC’s staff recommended that the three commissioners vote in favor of the New England Clean Energy Connect project. The $1 billion venture already has been endorsed in a settlement agreement at the PUC by some major participants in the case, including Gov. Janet Mills and the Public Advocate’s Office.

The project has met strong opposition from many residents in the area, as well as some environmental groups and power generators. Their concerns range from the impact of the 150-foot transmission corridor on the North Woods to unfair market competition. Advocates, however, see the line as a chance to bring a large amount of renewable energy into New England to combat climate change.