Opponents of a proposal to replace the state’s privately owned electric companies with a consumer-owned utility have crafted a referendum that could create a new hurdle.

Opponents of the proposal to buy out Maine’s two privately held electric utilities are launching a referendum effort to require voter approval of the cost of  completing such a purchase.

Political action committee Maine Affordable Energy, whose backers include Central Maine Power Co., filed an application Tuesday with the Maine Secretary of State’s Office to begin the process of gathering signatures to put a referendum on the ballot that would require voter approval before any government entity could take on $1 billion or more in debt.

Supporters of a consumer buyout of CMP and Versant Power also will be gathering signatures this fall to try to put their plan on the ballot. A proposal to create an entity known as Pine Tree Power Co. to pursue the buyout passed the Legislature early this year but was vetoed by Gov. Janet Mills, and supporters were unable to secure enough votes to override the veto.

Both efforts will require supporters to gather more than 63,000 signatures to put a measure on the 2022 or 2023 general election ballot.

A purchase price for the utilities has not been determined and likely would need to be settled in court, but it is expected to be in the billions of dollars.

Maine Affordable Energy is backed by CMP, but so far the utility hasn’t donated any money to the referendum effort. However, CMP did donate nearly $450,000 to the group when the buyout proposal was before the Legislature this year for “grassroots lobbying” against that proposal, mainly encouraging voters who opposed a public purchase of the utilities to call their state lawmakers.