AUGUSTA — A bid to require additional scrutiny of Central Maine Power’s controversial transmission line proposal faltered in the Maine House on Tuesday.

Opponents of CMP’s proposed 145-mile transmission line have been calling for an independent study of the project’s impact on greenhouse gas emissions in Canada and New England. Project opponents hoped such a study could affect permitting decisions for the controversial project in western Maine.

While CMP and other backers contend the project will reduce emissions, opponents question whether Hydro-Quebec will have to replace or supplement its hydropower with generation from non-renewable sources to supply Massachusetts ratepayers with the amount of “clean” electricity they plan to purchase.

As an “emergency measure,” the bill to require an independent study needed a two-thirds vote in the Maine House on Tuesday. But it fell far short of that threshold on a vote of 77-66.

Lawmakers opposed to the study said it was nothing more than another attempt to delay or derail the project. But bill supporters said the bill would not delay the remaining permitting process for CMP’s project because the study would have to be completed by mid-August – an expedited timeline that necessitated passage of the bill as an “emergency measure.”