Washington attorney Steve Bisker, a former NCUA assistant general counsel, said he came to that conclusion after looking at HarborOne's preliminary online notice filed with regulators.

“The stated 'consequences of conversion' are inaccurate or misleading at best,” Bisker said, pointing to what he said are inconsistencies on its stated need for more capital to lend and its prospects for increased membership under a mutual charter.

Since posting a Feb. 16 notice on its website telling members of a “possible conversion to a cooperative mutual,” the CU has not returned phone calls from Credit Union Times seeking comment.

Blake has told Boston media that HarborOne's field of membership is limited to four counties, and that HarborOne has been forced to turn down $70 million in mortgages and other consumer loans from potential members who live outside its market.

The website notice said HarborOne's board would meet March 21 to further consider the conversion plan. The notice solicited comments from members and said a switch could take place by September if regulatory and legal hurdles are cleared.

According to insiders and statements made by HarborOne, the reasons for converting include capital and loan restraints, FOM restrictions and unease over onerous regulatory burdens, the result of new NCUA policies as it seeks to comply with the Dodd-Frank Act and other new statutes.

The co-op bank structure would empower the metro Boston CU to expand business loans and mortgages, increase capital and branch into downtown Boston and elsewhere in the state, the credit union said.